IS militants push closer towards Syria's Aleppo

The Islamic State group [IS] advanced to the Syrian city of Aleppo early on Friday, after hours of ferocious fighting, bringing the militant group the closest it has been to the city, a monitor has reported.

"Dozens of combatants were killed on both sides," said Rami Abd al-Rahman of the Syrian Observatory for Human Rights.

After a night of fierce clashes, IS militants had driven out rebels from the localities of Tall Qrah, Tall Soussin, Kafar Qares and the base of Madrasat al-Mushat by early morning.

The seizure of these positions brought the militants to about 20 kilometres from the front line where forces loyal to President Bashar al-Assad are positioned, including the Sheikh Najjar industrial zone.

"IS has never been so close to the city of Aleppo, and this is its biggest advance towards" the country's pre-war commercial capital, said Rahman, whose Britain-based group relies on a network of sources on the ground across Syria.

IS have claimed territory mostly to the north-east of Aleppo, where it controls towns and regions including al-Bab, one of its strongholds.

The conflict began as an uprising against Assad's rule in 2011 but has splintered into a multi-faceted civil war involving government troops, Western-backed rebels, Islamic militants and Kurdish forces.

More than 240,000 people have been killed, with four million more forced to flee the country.

Iranian commander killed

Iran's Revolutionary Guards in Syria announced on Friday that IS militants killed a senior commander of the elite military regiment.

	Iran has sent Revolutionary Guards to aid Assad [Getty]

General Hossein Hamedani was killed on Thursday by IS "during an advisory mission" in the northern region of Aleppo, a Guards statement said.

Hamedani had been playing an "important role, reinforcing the front of Islamic resistance against the terrorists", it added.

Iran is a staunch ally of Assad, sending Guards forces and military advisers to aid him against rebels seeking his overthrow.

Lebanon's militia Hizballah has done much of the fighting to prop up the Syrian army, though the commander of the Revolutionary Guards' foreign wing, Qassem Soleimani, is said to be heavily involved in guiding military strategy.

IS kills Assyrian Christian captives

Meanwhile, IS militants appear to have killed three Christian captives in Syria and are threatening to kill 200 more held hostage if their ransoms are not paid, the Syrian Observatory for Human Rights also said.

The men were captured in February when IS overran a series of Assyrian settlements on the Khabur river in north-east Syria – villages that were populated in the early 20th century by Assyrian Christians fleeing Turkish genocide.

A video released by the group shows the men dressed in orange jumpsuits before they are shot dead. One of the men says IS will begin executing other prisoners if the militants' demands are not met.