The foreign secretary, William Hague, is expected to press his Russian counterpart on the spiralling crisis in Syria during his one-day visit to Moscow.

Although long-planned, the visit gained new urgency following the weekend massacre in Houla, when more than 90 people, including 32 children, were killed in an attack claimed to have been backed by the regime of Bashar al-Assad.

"Our urgent priority is to establish a full account of this appalling crime and to move swiftly to ensure that those responsible are identified and held to account," Hague said on Sunday, pledging a "strong response" to the massacre.

"In Moscow tomorrow [Monday]. Will call on Russia to support rapid & unequivocal pressure on Assad regime and accountability for crimes," he said in a Twitter message late on Saturday.

Russia has firmly backed Assad, blocking UN sanctions on his regime. Syria is Russia's main ally in the Middle East and home to its only military base outside the former Soviet Union. Russia maintains that on principle it rejects what it sees as western meddling in the domestic affairs of sovereign nations. It continues to supply weapons to Syria despite international outcry.

Russia's support would be key to a new plan being proposed by the Obama administration that would involve Assad peacefully leaving power while leaving the structure of his government intact, the New York Times reported over the weekend.

During his one-day visit to Moscow, Hague is also due to meet "other senior interlocutors", British sources have said, declining to provide details.

"He will engage them on a wide range of issues of concern to Britain and Russia – chief among them the situations in both Iran and Syria," a source said.