President Donald Trump revealed highly classified information to Russian diplomats in a meeting at the White House on 10 May, a new The Washington Post report claims. Current and former US officials said the disclosures placed a critical source of intelligence on the Islamic State (Isis) at risk.

According to the Washington Post, the information Trump passed on was given to the US by a partner in an intelligence-sharing arrangement believed to be so sensitive that details were not shared with allies and was guarded within the government, officials said. The US had not received permission from its partner to share the intel with Russia.

Officials noted that the president's decision to disclose the sensitive information to the Russians could risk cooperation from an ally with access to Isis. Senior White House officials were forced to call the CIA and the National Security Agency following the meeting to mitigate the damage.

"This is code-word information," a US official familiar with the matter told the Post. The term used by the official refers to one of the highest classifications levels used by US spy agencies. The president "revealed more information to the Russian ambassador than we have shared with our own allies."

Trump's revelations to the Russians come as his administration faces backlash for his decision to fire FBI director James Comey. The director was leading the charge on a bureau investigation into connections between the Trump campaign and Russia.

A day after Comey's sacking, Trump welcomed Russian Foreign Minister Sergei Lavrov and Ambassador Sergey Kislyak into the Oval Office. Trump was criticised for his decision to only allow Russian journalists to document the meeting.

The Post noted that as president, Trump has the authority to declassify government secrets, therefore making it unlikely that his disclosures to the Russians was illegal.

"The president and the foreign minister reviewed common threats from terrorist organisations to include threats to aviation," HR McMaster, the national security adviser who participated in the meeting, said. "At no time were any intelligence sources or methods discussed and no military operations were disclosed that were not already known publicly."

During the meeting, Trump is said to have gone off book and discussed details about an Isis threat dealing with the use of laptop computers on aircraft. Trump allegedly appeared to be boasting about his intel regarding the threat. "I get great intel. I have people brief me on great intel every day," he said, according to an official with knowledge of the exchange.

Trump then went on to open up about the aspects of the threat that the US learned through the spying of its key partner. While he did not reveal the specific intelligence gathering method, Trump spoke on how Isis was moving forward on different elements of a specific plot. He also revealed the city in Isis' so-called caliphate where the US intelligence partner detected the threat.

This particular knowledge could help Moscow identify the US intelligence partner and possibly disrupting it, the Post reported. "I don't think that it would be that hard [for Russian spy services] to figure this out," a former intelligence official said.

Officials declined to reveal who the ally was but noted that it was was one who had previously complained about Washington's inability to guard information relating to Iraq and Syria. "If that partner learned we'd given this to Russia without their knowledge or asking first that is a blow to that relationship," the US official told the Post.