Pentagon officials scrambled Tuesday to clarify how many US troops are in Syria after a general put the number at a "little over 4,000" -- far higher than previous tallies.

"I think it's a little over 4,000 US troops in Syria right now that are supporting efforts against," the Islamic State group, Army Major General James Jarrard told Pentagon reporters in a briefing about the anti-IS fight in Iraq and Syria.

When pressed on the issue, Jarrard backtracked. For months, the official number has only been 503.

"I'm sorry. I misspoke there. There are approximately 500 troops in Syria," he said.

But that number is not accurate either. It refers to what the military calls the "force management level" -- a bare minimum that does not include certain categories of personnel, such as when incoming and outgoing units temporarily overlap in the country.

A US official told AFP on condition of anonymity the actual number currently is more than 1,000.

And in Iraq, the official US presence is 5,262 -- but again officials acknowledge a bigger footprint.

The precise numbers stem from the Barack Obama era, when the former president wanted to keep the US presence in Iraq and Syria down.

Under President Donald Trump, battlefield commanders have been given greater flexibility to flow troops across the region, making it harder to track figures.

source: AFP