British foreign minister William Hague on Thursday urged Russia and Iran to use their influence over Syria to achieve a peaceful end to the bloody 15-month uprising against President Bashar al-Assad.
Hague met his Russian and Iranian counterparts in Kabul on the sidelines of a conference on the future of Afghanistan and stressed the need for the implementation of a peace plan proposed by international peace envoy Kofi Annan.
Russia is a long-term ally of Syria and has refused to stop supplying arms to Assad's regime, which is engaged in a bloody fight against the uprising that erupted in March 2011.
Monitors say more than 14,000 people have been killed. Moscow came under fierce criticism from Western and Arab countries for vetoing two UN Security Council resolutions that would have sanctioned Assad for his use of force.
"The foreign secretary asked Russia to use its full influence on the Syrian regime to ensure a peaceful resolution of the situation through a political process," Hague's ministry said in a statement.
Hague told his Russian counterpart Sergei Lavrov he welcomed in principle Moscow's plan for an international conference on Syria, the British Foreign Office said, but warned that Iran's presence was "probably unworkable".
Iran has been a staunch supporter of the Assad regime. Experts believe its help goes beyond diplomatic and humanitarian aid to include covert military assistance.
Briefing reporters on Wednesday, Hague said that where Russia appeared keen to want to resolve the Syrian bloodshed, Iran was in a different position which made its attendance at any conference difficult.
"We haven't at any stage detected Iran being a country that wants to solve the problem rather than exacerbating the problem," he said.
Relations between London and Tehran are in the deep freeze after Britain expelled Iranian diplomats in response to an assault on the British embassy in Tehran.
In what London described as a brief meeting with Iranian Foreign Minister Ali Akbar Salehi, Hague called on Iran to "use its influence in support of full implementation of the Annan plan."
UN peacekeeping chief Herve Ladsous said Tuesday that Syria was at civil war -- the most senior UN official to say so.