A still image, taken from video footage and released by Russia's Defence Ministry on August 18, 2016, shows a Russian Tupolev Tu-22M3 long-range bomber landing at an air base near the Iranian city of Hamadan. Ministry of Defence of the Russian Federation/Handout via REUTERS TV

DUBAI (Reuters) - Iran has again allowed Russian planes to use its airspace during recent operations in Syria, a senior Iranian security official was quoted as saying on Saturday.

In August, Russian aircraft for the first time used an Iranian air base to conduct strikes in Syria. The Russian military said its fighters had completed their tasks, but left open the possibility of using the Hamadan base again if circumstances warranted.

Iran’s Foreign Ministry said then that Russia had stopped using the base for strikes in Syria, bringing an abrupt halt to the deployment that was criticized both by the United States and some Iranian lawmakers.

Ali Shamkhani, secretary of Iran’s National Security Council, on Saturday told the semi-official news agency Fars: “Their (Russians’) use of Iran’s air space has continued because we have a fully strategic cooperation with Russia.”

“In the recent cases, Russian fighter planes have only used Iran’s airspace and have not had refueling operations,” Shamkhani added.

The agency said Shamkhani was commenting on media reports that Russia’s Tupolev-22M long-range bombers had used Iranian airspace and a base in the country on their missions in Syria, where both Tehran and Moscow back President Bashar al-Assad’s government.

It was not immediately clear if the recent missions were linked to Russian air strikes on Thursday that accidentally killed three Turkish soldiers during an operation against Islamic State in Syria, according to the Turkish military.