Washington, Oct 23 (IANS): The US-led coalition fighting the Islamic State (IS) terror group in Syria conducted two strikes against two "command centres" that were operating inside mosques in Abu Kamal district in less than a week, it said in a statement.

The coalition said on Monday that 12 IS fighters were killed in the first strike, which took place Oon ctober 18 in Al-Susah town, reports CNN.

"The facility was a mosque, which the law of war protects from targeting unless it is used for a military purpose," the coalition said, adding that the IS "repeatedly planned and actively coordinated attacks" on coalition troops and their local Syrian allies from that location.

The second strike took place in the same town on Monday. It "destroyed several buildings" used by the IS to launch attacks against Syrian Democratic Force partners.

"They're nasty, they're brutal, they're unethical and they certainly have no problem at all putting civilians at risk and jeopardising the status of protected targets," Pentagon spokesman Col. Rob Manning told the media on Monday when asked about IS' use of mosques as military facilities.

US-led coalition military forces have conducted hundreds of strikes against IS targets in Syria as the US and its local Syrian allies seek to drive the terror group from its last remaining stronghold east of the Euphrates river.

The coalition has assessed that over 1,000 civilians have been killed by coalition strikes since the campaign against IS began in 2014.

However, outside monitor groups believe that number is higher.