America is committed to fighting "crimes against the innocents" across the globe, US Secretary of State Rex Tillerson has said.

He spoke during a memorial in the Tuscan town of Sant'Anna di Stazzema to mark a Nazi 1944 massacre, ahead of a G7 foreign ministers meeting in nearby Lucca, Italy.

Image: The Sant'Anna di Stazzema memorial in Tuscany

Foreign ministers from France, Canada, Japan, Germany, Italy and the UK will join Mr Tillerson for talks on how to sever the close ties between Syria's Bashar al Assad and Russian president Vladimir Putin.

"We will dedicate ourselves to holding to account any and all who commit crimes against the innocents anywhere in the world," said Mr Tillerson in Tuscany.

His comments ahead of a trip to Moscow followed condemnation from Russia and Iran on US airstrikes in Syria after a chemical weapons attack which killed more than 80 people, including up to 30 children.


Mr Putin and Iranian leader Hassan Rouhani warned the US a "red line" had been crossed.

West souring Russia relations over Syria

The attack was seen to mark a dramatic departure from Donald Trump's "America First" philosophy and represent a much more aggressive foreign policy.

British Foreign Secretary Boris Johnson, in Tuscany for the annual summit, warned the US could launch further airstrikes on Syria following its bombing of the Shayrat airfield near the city of Homs on Friday.

A spokesman for Prime Minister Theresa May said Britain was "in discussions with our key partners on how we can bring further pressure to bear on the regime and those who are backing it, which includes the Russians".

He refused to be drawn on whether the UK would support further US military action in Syria.

What changed Trump's mind about Assad?

"What we are focused on is building international support for a political solution to end the conflict and bring lasting peace and stability to Syria," he said.

Meanwhile, the Kremlin said mantras such as "Assad should leave" would not help resolve the crisis.

Mr Putin's spokesman Dmitry Peskov added that Mr Tillerson would be meeting his Russian counterpart Sergey Lavrov and not the Russian president.

Mr Tillerson will deliver a "clear and coordinated" message to the Kremlin after Mr Johnson cancelled his own visit to the Russian capital following conversations with Mr Trump's team.