Vladimir Putin has claimed he has information that the United States is planning a fresh wave of airstrikes in Syria.

The Russian president said Moscow had also received intelligence about planned fake chemical weapons attacks with the sole purpose of pinning the blame on Bashar al Assad's regime.

Russia has rejected suggestions from the outset that the Syrian government was behind a gas attack in Idlib province which killed more than 80 people, including many children.

The US retaliated with airstrikes on a Syrian airbase from which it believes the chemical attack in the rebel-held town of Khan Sheikhoun was launched.

Both the Syrian regime and Russia have denied they were involved.

Mr Putin appealed to the United Nations to launch an official investigation into the attack.

He compared the allegation levelled at Mr Assad to how the US justified its intervention in Iraq in 2003.

Claims that Saddam Hussein's regime had weapons of mass destruction were never proven.

His comments came as Turkey confirmed sarin gas was used in the attack in northern Syria - and US Secretary of State Rex Tillerson arrived in Moscow for crucial talks on "a solution which will deliver a lasting political settlement" in Syria.

G7 foreign ministers earlier rejected calls to broaden sanctions against Russia and Syria.