Russia said on Saturday it had told the United States it was unacceptable for Washington to strike pro-government forces in Syria.

:: Russia said on Saturday it had told the United States it was unacceptable for Washington to strike pro-government forces in Syria after the US military carried out an air strike on pro-Assad militia last month.

Russian Foreign Minister Sergei Lavrov relayed the message to US Secretary of State Rex Tillerson in a phone call on Saturday initiated by the US side, the Russian Foreign Ministry said in a statement.

US officials told Reuters last month that the US military carried out the air strike against militia supported by the government of President Bashar al-Assad which it said posed a threat to US forces and US-backed Syrian fighters in the country’s south.

Russia said at the time that the US action would hamper efforts to find a political solution to the conflict and had violated the sovereignty of Syria, one of Russia’s closest Middle East allies.

“Lavrov expressed his categorical disagreement with the US strikes on pro-government forces and called on him to take concrete measures to prevent similar incidents in future,” the ministry said.

The two men had also exchanged assessments of the situation in Syria, it added, and confirmed their desire to step up co-operation to try to end the conflict there.