Vladimir Putin warns of chemical weapons 'provocations' to frame Assad

Russian President Vladimir Putin on Tuesday warned of future chemical weapons "provocations" in Syria to frame President Bashar al-Assad, just as Washington's top diplomat arrived for talks in Moscow.

"We have information from various sources that such provocations -- I cannot call them otherwise -- are being prepared in other regions of Syria, including in the southern outskirts of Damascus, where they are again planning to throw some kind of substance and accuse Syrian official authorities of using it," Putin said at a televised press conference.

He said Russia was set to appeal to the Organisation for the Prohibition of Chemical Weapons and "call on the international community to thoroughly investigate such incidents".

Putin insisted that reports over the suspected chemical attack in Syria that killed dozens of people in the rebel-held town of Khan Sheikhun last week was reminiscent of the 2003 US-led invasion of Iraq, justified by the alleged existence of weapons of mass destruction.

"This ended with the country's destruction, with the growth of the terrorist threat and the appearance of the Islamic State on the international stage, no more, no less," he said.

Russia's defence ministry also said it had information that rebel fighters were bringing "poisonous substances" to the areas around the Syrian town of Khan Sheikhun and Eastern Ghuta, among other places.

"The goal of these actions is to create yet another reason to accuse the Syrian government of using chemical weapons and provoke new strikes by the United States," it said in a statement.

The latest claims came as US Secretary of State Rex Tillerson touched down in Russia to confront the Kremlin over its support for Assad on the first visit by a senior member of Trump's administration.

Putin said Russia and Syria were being portrayed as a "common enemy" in a bid to bring together the United States and its Western allies after many leaders criticised Trump ahead of his election.

"We are ready to tolerate this, but we hope that this will nonetheless lead to some kind of positive cooperation trend," he said.

Moscow has sought to deflect blame from its long-time ally Assad over the alleged chemical attack and says Syrian jets struck a rebel arms depot where "toxic substances" were being put inside bombs.

Following on from the Tillerson visit, Moscow has announced Lavrov will host three-way talks with his counterparts from Syria and Iran later this week.