Trump claims 'absolute right' to share 'facts' with Russia

President Donald Trump has defended his "absolute right" to share information with Russia, following a row over classified material, even as US National Security Adviser HR McMaster challenged reporting of the Oval Office meeting

Trump tweeted that he had only shared "facts pertaining to terrorism and airline safety" and wanted Russia to do more against so-called Islamic State.

"As President I wanted to share with Russia (at an openly scheduled WH meeting) which I have the absolute right to do, facts pertaining to terrorism and airline flight safety,'' Trump tweeted early on Tuesday.

"Humanitarian reasons, plus I want Russia to greatly step up their fight against IS & terrorism," he added.

Reports quoting two US officials on Monday said that President Donald Trump during his meeting with Russian foreign minister Sergei Lavrov and Russian ambassador Sergei Kislyak disclosed highly classified information about a planned Islamic State operation.

The intelligence, shared at a meeting last week with the Russian minister, was supplied by a US ally in the fight against the militant group, reports quoted the officials as saying.

US media reports said Trump had passed on the material to Russia without permission from the ally, which had shared it with the US.

A report in The Washington Post said Trump had confided top secret information relating to an IS plot thought to centre on the use of laptop computers on aircraft.

The paper quoting government officials said the details passed on by the President to Russia could lead to the exposure of a source of information.

Speaking to the BBC, Post reporter Greg Jaffe said the story made it clear the president did not disclose sources or methods. But, he added, "Our story says that the nature of the information provided would have allowed the Russians to 'reverse engineer' to discover the sources and methods. He said so much that they could figure it out."

While Trump's move is not illegal, as the US president has the authority to declassify information, the action drew strong criticism from Democrats and a call for an explanation from his own Republican party.

The report also drew comments by US allies in the Nato, with a senior diplomat quoted by Reuters saying, "If true, this is not going to instill confidence in allies already wary of sharing the most sensitive information."

Interestingly, Trump's meeting with the Russian officials came a day after he fired FBI chief James Comey, sparking criticism that he had done so because the FBI was investigating alleged Russian ties.

Despite White House denials and clarifications by The Washington Post, what transpired at the Oval Office meeting was enough to alarm officials and alert the CIA and NSA.