Russian and US armed forces must "cooperate on the ground" in Syria to facilitate a truce and humanitarian access agreed by world powers, Russia's Foreign Minister Sergei Lavrov said Friday.

"For this to work... cooperation between the militaries on the ground is needed, both on humanitarian issues and issues related to implementing the ceasefire," state news agency RIA Novosti quoted Lavrov as saying.

"From the very beginning of our operation in Syria at the invitation of the country's government, we proposed military contacts between Russia and the US-led coalition," he said in the German city of Munich where the Syria agreement was struck.

US Secretary of State John Kerry and Lavrov led 17 nations in hammering out the deal aimed at reviving the peace process for the five-year-old conflict.

Moscow strongly backs the regime of President Bashar al-Assad, while the US and its allies have called for its removal.

"Now it's important to implement what has been agreed because sometimes we come to an agreement but our partners do not seek to honour that agreement in practice," Lavrov said.

"I am hoping that this time things will be different."

The United States has also led a multinational alliance targeting the Islamic State jihadist group in its self-proclaimed caliphate stretching across a swathe of Syria and Iraq.

While Russia also says it is targeting IS, the West has accused it of striking all rebels fighting Assad, including moderates.

"Unfortunately, the United States avoided cooperation in the military sphere except on issues related to procedures to avoid conflict," Lavrov said.

"But now -- I believe -- they realised that to move forward in the Syrian settlement one can no longer avoid contacts between the militaries."

Kerry announced earlier that a UN task force, co-chaired by Russia and the US, will work over the coming week "to develop the modalities for a long-term, comprehensive and durable cessation of violence".

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