Syrian chief negotiator Bashar al-Jaafari, left, Ambassador of the Permanent Representative Mission of Syria to the UN New York, and UN Special Envoy of the Secretary-General for Syria Staffan de Mistura, right, sit no their tables prior to a round of negotiations between the Syrian government and U.N., at the European headquarters of the United Nations in Geneva, Switzerland, Friday, March 18, 2016. (Salvatore Di Nolfi/pool photo via AP)
Syrian chief negotiator Bashar al-Jaafari, left, Ambassador of the Permanent Representative Mission of Syria to the UN New York, and UN Special Envoy of the Secretary-General for Syria Staffan de Mistura, right, sit no their tables prior to a round of negotiations between the Syrian government and U.N., at the European headquarters of the United Nations in Geneva, Switzerland, Friday, March 18, 2016. (Salvatore Di Nolfi/pool photo via AP) Credit: SALVATORE DI NOLFI

BEIRUT — Backed by Russian aircraft, Syrian troops pushed Friday toward the historic central town of Palmyra in an offensive to recapture it from the Islamic State group whose fighters have damaged some of the world’s most precious archaeological sites since they overran the town last May.

After night fell, Syria’s state news agency SANA reported that the offensive advanced toward Palmyra and that scores of IS fighters have been killed or wounded in Syrian artillery fire near the town. The reports gave no casualty numbers or other details.

Activists who monitor the Syrian conflict reported intense airstrikes in Palmyra and its suburbs. In Moscow, a Russian Defense Ministry official confirmed his country’s warplanes in Syria were flying in support of the Syrian offensive.

Lt. Gen. Sergei Rudskoi said Russian aircraft were conducting 20-25 sorties a day in support of the Palmyra offensive, even though Russia this week drew down its military presence in Syria after President Vladimir Putin ordered a partial pullout of Russian aircraft and forces from Syria, in support of the Geneva peace talks.

The U.N.-brokered talks between representatives of the Syrian government and the Western-backed opposition adjourned for the weekend after five days of proximity discussions.

Though Rudskoi’s statements indicated that Russian aircraft supporting the Palmyra offensive were carrying out airstrikes, U.S. military officials raised doubts.