Isis leader Abu Bakr al-Baghdadi has been confirmed killed, war monitor the Syrian Observatory for Human Rights (SOHR) has said.

"(We have) confirmed information from leaders, including one of the first rank, in [Isis territory] in the eastern countryside of Deir Ezzor," director of the UK-based group Rami Abdulrahman told Reuters on Tuesday.

However, there has been no confirmation from Isis' official news agency Amaq. SOHR's sources did not say when Baghdadi supposedly died, or how, except that he is supposed to have been living in the Deir Ezzor area for the last three months.

The Pentagon, Kurdish and Iraqi sources were all quick to say they could not corroborate the SOHR report.

"We take any report of this nature with a large dose of salt," Sebastian Gorka, deputy assistant to US President Donald Trump, said in an interview with Fox News after the SOHR claim surfaced.

"We will verify it. We will look at the intelligence available... and we will give a statement when we have the requisite facts."

The US put up a $25 million (£19 million) reward for Baghdadi's capture - the same it has offered for al Qaeda leaders Osama bin Laden and his successor Ayman al-Zawahri.

It is not yet known if any individual or organization will claim the bounty.

The notorious jihadi is believed to be in hiding in the region around the Syria-Iraq border, moving frequently and avoiding telecommunications to evade detection.

Rumors of his death have been reported frequently since the cleric made his only public appearance announcing the creation of Isis' so-called caliphate from the Iraqi city of Mosul in 2014.

In June, the Russian Foreign Ministry claimed to have carried out an air strike in Syria which killed Baghdadi and several other high profile Isis leaders, but did not provide any evidence backing up the claim.

At the time, Washington DC said it could not corroborate the death, and Western and Iraqi officials have been skeptical.

UK-based SOHR is a respected human rights and war crimes monitor utilising sources on the ground in Syria with a credible track record reporting on the civil war.

If the report is true, it comes as one of the biggest blows yet to the jihadist organisation which is rapidly losing territory across Syria and Iraq.

Last week the Iraqi army officially declared Isis' de facto Iraqi capital of Mosul liberated from the militants, marking the destruction of one half of the so-called caliphate.