Germany's top diplomat calls for an end to Qatar blockade imposed by Saudi-led Arab states

Germany's foreign minister has called for an end to a land, sea and air blockade imposed on Qatar by a Saudi-led clique of Arab countries with grudges against Doha, urging for all sides to negotiate a solution.

Sigmar Gabriel made the remarks on Friday after a meeting with his Qatari counterpart Sheikh Mohammed bin Abdulrahman Al Thani in the German town of Wolfenbuettel.

"Along with our American colleagues but above all our colleagues in the region, we must try to find solutions, especially lifting the sea and air blockades," Gabriel told reporters.

"We are convinced that now is the hour of diplomacy and we must talk to each other,"

He added that it was important to prevent any "further escalation" and that Berlin was willing to help with diplomatic efforts being arranged by the US, Kuwait and others.

US President Donald Trump on Thursday offered Secretary of State Rex Tillerson to mediate the standoff between Qatar and the Saudi-led coalition that has severed ties with the tiny country over support for extremist groups.

Tillerson, who dealt with Qatari leaders for years as chief executive officer of Exxon Mobil, is skilled at bringing people together and is ready to help if needed, State Department spokeswoman Heather Nauert said on Thursday. She added that Trump would rather that all sides work out the dispute among themselves.

The announcement came after Trump met with Tillerson and Defence Secretary Jim Mattis at the White House earlier on Thursday to discuss the crisis.

Saudi Arabia, the United Arab Emirates, Egypt and Bahrain led a string of countries that this week cut ties with Qatar over what they say is the emirate's financing of extremist groups and its ties to Iran, Saudi Arabia's regional arch-rival.

Qatar denies having any ties to extremists.

The Arab countries have closed air, sea and land links with Qatar, barred the emirate's planes from their airspace and ordered Qatari citizens out within 14 days.

Qatar's foreign minister said during the joint press conference that the sanctions imposed upon his country violate international law, calling the moves by Saudi Arabia and other Arab nations an "unjust siege."

"These procedures will not have a positive impact on the region but a negative one,"

He asked: "What crime did Qatar commit to deserve such a punishment that violates international law?"

Qatar on Friday dismissed as "baseless" a terrorism blacklist published by Saudi Arabia and its allies which linked individuals and organisations in Doha to support for Islamist militant groups.

The emirate was responding just hours after Saudi Arabia, the United Arab Emirates, Egypt and Bahrain published a list of 59 people and entities linked to "terrorism".