Russia's foreign ministry says Moscow will attend talks on the Syrian crisis organized by Iran.

The ministry says that Russia will be represented by its ambassador in Tehran if the talks set for Thursday take place. It said in a statement late Wednesday that the meeting was called at short notice, leaving little time to prepare.

Russia in the past has urged the West to allow Tehran to take part in international discussions on how to settle the crisis, arguing that the Islamic republic could play an important role.

Russia has been the main protector and ally of Syrian President Bashar Assad's regime, shielding it from the United Nations sanctions over its brutal crackdown on an uprising that evolved into a full-blown civil war.

THIS IS A BREAKING NEWS UPDATE. Check back soon for further information. AP's earlier story is below.

Activists say clashes between Syrian government troops and rebels are raging in the opposition bastion of Saleheddine and other districts of the besieged city of Aleppo.

The fighting comes just a day after President Bashar Assad's regime claimed in state-run media that its forces have fully regained control of Salaheddine.

The Local Coordination Committees and the Syrian Observatory for Human Rights said Thursday's shelling was most focused on Salaheddine, as well as a northeast district and areas in the city's southwest.

Syria launched a ground assault Wednesday on rebel-held areas of Aleppo, the country's largest city and key commercial hub.

The regime's blistering attacks on rebel positions in recent weeks seem to have chipped away at the opposition's grip on its strongholds in the city.