Russia’s Defence Ministry said on Thursday that the shelling of the Syrian city of Aleppo on Wednesday Feb. 10 was carried out by two U.S. aircraft and that Russian planes had not been operating in the area.

A Pentagon spokesman had blamed Russian and Syria government forces on Wednesday of targeting Aleppo’s two main hospitals with air strikes, without specifying when the strikes were alleged to have taken place.

In recent weeks, the Syrian army has been able to advance quickly near Aleppo with the help of Russian air strikes.

But Defence Ministry spokesman Igor Konashenkov said in a statement that “only aviation of the anti-ISIS coalition flew over the city yesterday”, referring to the U.S.-led alliance of countries fighting the ISIS militant group.

“At 1355 Moscow time, two U.S. Air Force A-10 attack aircraft entered Syrian airspace from Turkish territory. Reaching Aleppo by the most direct path, they made strikes against objects in the city.”

He said the Russian targets on that day had been at least 20 km (12 miles) from the city.

On the other hand, the U.S. State Department refuted on Thursday the Russian statement.

“Claims made by Russian officials of U.S. air strikes in Aleppo are false,” a senior State Department official said.

“There have been no U.S. missions flown in or around Aleppo today.”

Members of the United Nations Security Council urged Russia on Wednesday to stop bombing Aleppo in support of the Syrian military offensive and allow humanitarian access ahead of a meeting of major powers in Germany on the conflict.