LONDON (REUTERS, AFP) - British Prime Minister Theresa May told United States President Donald Trump she had "deep concern"about the expected announcement of US tariffs on aluminium and steel, Mrs May's office said on Sunday (March 4) following a phone call between the two leaders.

"The Prime Minister raised our deep concern at the President's forthcoming announcement on steel and aluminium tariffs, noting that multilateral action was the only way to resolve the problem of global overcapacity in all parties' interests," a spokesman from Mrs May's office said.

The two leaders also discussed the "appalling humanitarian situation in Eastern Ghouta" in Syria.

Russia and Syria are responsible for the "heart-breaking human suffering" in the Syrian rebel-held enclave of Eastern Ghouta, Mr Trump and Mrs May said.

"They agreed it was a humanitarian catastrophe, and that the overwhelming responsibility for the heart-breaking human suffering lay with the Syrian regime and Russia, as the regime's main backer," the prime minister's office said.

Syria's regime has seized control of over a quarter of Eastern Ghouta, on the edges of the capital Damascus, the Syrian Observatory for Human Rights said on Sunday.

Mrs May and Mr Trump said "Russia and others with influence over the Syrian regime must act now to cease their campaign of violence and to protect civilians".

The Syrian government's advance on Eastern Ghouta comes after 15 days of devastating air strikes, artillery fire and rocket attacks that are reported to have left more than 640 civilians dead.