The Palestinian group Hamas has launched the biggest attack on Israel in years, killing more than 100 people in a surprise operation that included fighters entering Israel by land, sea and air using paragliders after a barrage of rockets fired from the Gaza Strip.
Israeli attacks on the Gaza Strip have also killed 198 Palestinians and injured over 1,600 in Gaza, the Palestinian health ministry.
Israel said that Hamas had declared war and Prime Minister Benjamin Netanyahu has promised to "retaliate".
The major attack by Hamas came as Saudi Arabia and Israel were working towards a US-brokered deal to normalise relations, after UAE, Bahrain and Morocco normalised ties in the controversial Abraham Accords agreement in 2020.
The assault by Hamas also came after recent deadly attacks by Israeli forces and Israeli settlers against Palestinians in the West Bank.
Here are reactions to the fighting so far from key Arab states:
Saudi Arabia
A statement by the Ministry of Foreign Affairs said that Saudi Arabia was "closely monitoring the unprecedented developments between various Palestinian factions and the Israeli occupation forces, resulting in an escalation of violence on several fronts".
It said Riyadh calls for "an immediate cessation of the escalation" between both sides and "the protection of civilians".
It said Saudi Arabia had issued repeated warnings of a possible escalation in light of "the ongoing occupation and the deprivation of the Palestinian people of their legitimate rights, as well as the repeated deliberate provocations against their sanctities".
It urged the international community to "fulfil its responsibilities and activate a credible peaceful process leading to a two-state solution that achieves security and peace in the region and protects civilians".
Qatar
Qatar, which has been starkly opposed to normalisation with Israel, expressed "deep concern" over the developments in the Gaza Strip.
A statement issued by the Ministry of Foreign Affairs said Israel was "solely responsible for the ongoing escalation due to its continuous violations of the rights of the Palestinian people, including its recent repeated intrusions into the holy Al-Aqsa Mosque under the protection of the Israeli police".
It called on the international community "to compel Israel to stop its blatant violations of international law, hold it accountable to respect legitimate international decisions and the historical rights of the Palestinian people, and prevent these events from being used as a pretext to ignite a new disproportionate war against Palestinian civilians in Gaza".
The statement reaffirmed Qatar's "consistent position in support of the Palestinian cause and the legitimate rights of the Palestinian people, including the establishment of their independent state based on the 1967 borders, with East Jerusalem as its capital."
UAE
The UAE expressed "deep concern" over the escalation in a statement that stressed the need "to stop the escalation and preserve the lives of civilians".
The statement offered "sincere condolences" to all the victims of the recent fighting.
It called for "the immediate reactivating of the international Quartet to revive the path of Arab-Israeli peace", and urged the international community to advance all efforts made to achieve comprehensive and just peace, and prevent the region from being dragged to "new levels of violence, tension and instability".
Late on Sunday, the UAE issued another statement slamming Hamas' attack as a "serious and grave escalation".
The UAE foreign ministry statement added that it was "appalled" by reports Israeli civilians were taken as hostages from their homes, but avoided criticism of Israel's deadly strikes on Gaza.
"Civilians on both sides must always have full protection under international humanitarian law and must never be a target of conflict," the ministry added.
Bahrain
Bahrain criticised the attacks by Hamas, saying they constituted "a dangerous escalation that threatens the lives of civilians", according to a foreign ministry statement on Monday.
The statement also affirmed "Bahrain's denunciation of the reported kidnappings of civilians from their homes to be taken as hostages" and urged for the de-escalation of the violence that threatens regional security and stability.
Kuwait
Kuwait expressed its "grave concern" over developments between Israel and the Palestinians, blaming Israel for what it called its "blatant attacks".
The foreign ministry in a statement called on the international community to "stop the provocative practices by the occupation" and the "policy of expanding settlements".
Oman
Oman called on Israel and the Palestinians to exercise maximum self-restraint, the state news agency reported quoting an official statement.
The statement asked the international community and international parties to "intervene immediately to stop the ongoing escalation and resort to the rules of international law".
Egypt
Egypt, which normalised with Israel in 1980 under a peace treaty, warned of "grave consequences" from an escalation in tensions between Israel and the Palestinians in a statement from the foreign ministry carried by the state news agency.
It called for "exercising maximum restraint and avoiding exposing civilians to further danger".
Egypt's Foreign Minister Sameh Shukri also held a call with European Union foreign policy chief Josep Borrell to discuss developments between Israel and the Palestinians since Friday evening, stating that both sides should exercise restraint to avoid serious risks.
Morocco
"The Kingdom of Morocco expresses its deep concern at the deterioration of the situation and the outbreak of military action in the Gaza Strip, and condemns attacks against civilians wherever they may be," a foreign ministry statement said.
Lebanon's Hezbollah
Lebanon's Hezbollah praised Hamas for its "heroic operation" in a statement.
"Hezbollah congratulates the resisting Palestinian people," the Lebanese Shia movement said in a statement, hailing Hamas and its armed wing, the Ezzedine al-Qassam Brigades, for the "large-scale, heroic operation".
Hezbollah said its leadership was following the developments and "in direct contact with the leadership of the Palestinian resistance at home and abroad".
Hezbollah said the Hamas operation in Israel was a "response to the continued crimes of the occupation and the continued assault on holy sites".
The Iran-backed group also said the Hamas operation was "a message to the Arab and Muslim world and the entire international community, especially those seeking normalisation".
In 2006 Hezbollah and Israel fought a 34-day war that left more than 1,200 dead in Lebanon, mostly civilians, and 160 in Israel, mostly soldiers.
Syria
The Syrian foreign ministry called the Hamas operation an "honourable achievement that proves the only way for Palestinians to obtain their legitimate rights is resistance in all its forms".
Syria also expressed its "support" for the Palestinian people and the forces "fighting against Zionist terrorism".
Yemen
Houthi rebels who control the capital Sanaa said they supported "the heroic jihadist operation".
In a statement published on the website of the Huthi-controlled SABA news agency, the Iran-aligned militant group said the attack "revealed the weakness, fragility and impotence" of Israel.
It called the operation "a battle of dignity, pride, and defence".
This article has been republished on 10 October to include the latest statements.