MOSCOW (Reuters) - A Russian marine major has been killed in combat in Syria, Russian news agencies reported on Thursday, confirming an earlier report that one of Moscow’s highest-ranking officers there had lost his life.

Major Sergei Bordov was killed during an attack by militants on a garrison, they said, quoting the Russian defense ministry. The reports gave no further details.

Earlier on Thursday, Reuters reported Bordov’s death, citing a former marine who had served with him and a person close to the Russian Black Sea Fleet.

Russian forces are backing Syrian President Bashar al-Assad in his war with rebels and militants seeking to oust him.

“They were caught in shell fire. Two of our Russian servicemen and two Syrian soldiers died,” Vyacheslav Pavlyuchenko, who has served with Bordov, told Reuters.

He said the shelling incident occurred on Tuesday and that he did not know the names of the other fallen soldiers.

Bordov is one of the highest-ranking Russian officers to be killed in Syria. Pavlyuchenko said Bordov commanded a reconnaissance company two years ago but he did not know the major’s current role in the Syria operation.

Bordov’s body was expected to be delivered to his military unit in the Crimean town of Sebastopol on Friday and his burial should take place in his hometown of Simferopol on Saturday, Pavlyuchenko and the source close to the fleet said.

The defense ministry says about 30 Russian servicemen have been killed since the start of the Kremlin’s operation there in September 2015.

Evidence collected by Reuters points to losses among Russian servicemen and private military contractors in Syria three to four times higher than some official estimates, although the defense ministry has denied understating the death toll.