The British premier and French president on Monday "expressed their desire" to work with Russia to find a resolution to the crisis in Syria, dpa reported.
A government spokeswoman in London said that British Prime Minister David Cameron was due to speak later Monday to UN Secretary General Ban Ki-moon.
In a telephone call, Cameron and French President Francois Hollande also expressed support for a meeting in Paris in the near future of the Friends of Syria group.
"Faced with this unacceptable situation and the regime's contempt for the ceasefire," said the spokeswoman, "the prime minister and president agreed to act together to increase the pressure of the international community on (Syrian President Bashar al-) Assad and to bring an end to the bloody suppression of the Syrian people who aspire to freedom and democracy."