Washington:The US has admitted to more civilian casualties in its airstrikes against alleged Daesh (ISIL) positions inside Syria and Iraq between September and February, amid reports that the Pentagon has increased civilian death tolerance in the two countries.

According to a statement on Friday by the US Central Command (CENTCOM), in the five-month period, a total of 20 civilians were killed and 11 others were injured as a result of air raids by the US-led coalition which started its aerial campaign in August 2014.

“In this type of armed conflict, particularly with an enemy who hides among the civilian population, there are going to be, unfortunately, civilian casualties at times,” CENTCOM spokesman Colonel Pat Ryder said.

The new announcement raises the official tally of civilians killed in the campaign to 41, with 28 more injured.

According to a USA Today report earlier this week, the Pentagon has passed new rules allowing higher levels of allowable civilian casualties in its military campaign against Daesh.

Six Pentagon officials, all speaking on condition of anonymity, told the paper that The Pentagon has delegated more authority to US Army Lieutenant General Sean MacFarland, head of the US-led coalition against Daesh in Iraq and Syria, to approve targets when civilians could be killed.

Meanwhile, Airwars, a UK-based airstrikes monitoring group, says the real number of US civilian victims exceeds 1000 people as the US and its allies have carried out more than 12,000 plane and drone strikes in Iraq and Syria, dropping some 40,000 bombs.

The group released a report in March, saying the UK-based group’s analysis of 352 coalition-related events leading to civilian casualties indicate that 1,004 to 1,419 non combatants have so far lost their lives in US-led airstrikes.

The London-based Syrian Observatory for Human Rights said on February 15 that US air assaults had claimed 38 lives in Syria’s Hasakah Province over a two-day period.

At least a dozen civilians were killed in two aerial assaults by US military aircraft in Mosul on December 21, according to eyewitness and medical sources.

Additionally, the US has admitted that on December 18, a number of Iraqi soldiers were killed in a so-called “friendly-fire” involving American fighter jets.

In another similar incident, US air raids in the Syrian town of Ayyash in Deir al-Zour province killed four Army soldiers in the Saeqa military camp, according to the so-called Syrian Observatory for Human Rights, which is affiliated to the foreign-backed Syria opposition.