SYRIA condemned US Secretary of State John Kerry’s threats to prolong the war and partition the country yesterday.

The Syrian Foreign Ministry said Mr Kerry’s remarks ran “counter to reality” and attempted to “conceal his country’s responsibility for the terrorist crimes that Syria has been subjected to.”

Syria’s Sana news agency reported that 18 civilians had been killed in the government-held western part of Aleppo city over the past 24 hours by shelling from the rebel-occupied east.

President Bashar al-Assad assured his Russian counterpart Vladimir Putin of Syria’s readiness to abide by the “cessation of hostilities” set to begin at midnight tomorrow.

But the two leaders committed to ongoing offensives against the UN-designated terrorist forces Islamic State (Isis) and Nusra Front.

Russia has already set up a ceasefire monitoring centre at its Khmeimim airbase in Latakia province.

On Tuesday Mr Kerry threatened Syria with a “Plan B” of sectarian partition, warning that things could get “uglier” if Mr Assad stays in power.

Mr Kerry told a sceptical Senate foreign relations committee hearing on the truce plan that the White House was working on a backup strategy “in the event we don’t succeed at the [negotiating] table.”

“This can get a lot uglier and Russia has to be sitting there evaluating that too,” he said.

Raising the spectre of redrawing the national borders set partly by the 1916 Sykes-Picot carve-up of the Ottoman empire, he said: “It may be too late to keep it as a whole Syria if we wait much longer.

“Assad himself is going to have to make some real decisions about the formation of a transitional government process that is real … there are certainly ‘Plan B’ options being considered.”

But committee chairman Republican Tennessee Senator Bob Corker countered: “Russia knows there will be no Plan B.”

Republican Kentucky Senator Rand Paul suggested abandoning Washington’s regime-change agenda, now a receding prospect in light of recent government victories following Russia’s five-month intervention in the war.

But Mr Kerry continued to insist that Mr Assad must go.

“As long as Assad is there, you cannot stop the war,” he claimed.

“How he’s somehow going to be the glue that brings the place together is beyond anybody’s understanding.”