DAMASCUS – A prominent Syrian rebel leader has died from wounds suffered in an air raid on the city of Aleppo last Thursday, in a blow to the rebels.

Abdul Qadir al-Saleh, the leader of Liwa al-Tawhid, died overnight, a spokesman said. The Tawhid Brigades is backed by Qatar.

Saleh died in a Turkish hospital where he had been taken.

Saleh had been wounded on Thursday when Assad’s forces raided a Tawhid meeting and killed another commander on the spot, opposition sources said.

“We declare the martyrdom of Abdelqader Saleh,” a statement by Tawhid said.

Liwa al-Tawhid is one of the main rebel forces in Aleppo and is estimated to have between 8,000 and 10,000 fighters.

Meanwhile, senior figures from the Syrian regime are in Moscow to discuss plans for a peace conference.

Deputy Foreign Minister Faisal Mekdad led the team, which has been meeting counterparts in the Russian foreign ministry.

Saleh, who was in his 30s, had been working on regrouping fighters in Aleppo before he died. The city, situated 45 kms south of Turkey, was Syria’s commercial hub and most populous city before the uprising against Assad erupted in 2011.

Taking advantage of infighting between rebel groups, Assad’s forces, backed by Shi’ite militia from Iraq and the Lebanese party Hezbollah, have been have been making advances in the north and east of the contested city.

In an interview with the Opposition Orient Television from a battlefield in eastern Aleppo last week, Saleh said: “We will not let Iran and Hezbollah advance except on our dead bodies.”

Saleh, a merchant from the town of Mareh in the countryside north of Aleppo, organized dozens of rebel brigades in the region under the Tawhid banner. A former army conscript, he was known

as the nom de guerre Hajji Mareh, reports Reuters.

Tawhid issued a statement last week, along with other Islamist formations that included al-Nusra Front, an al Qaeda affiliate, declaring an emergency and summoning all fighters to head to the fronts.

Opposition activists said the declaration was an indication of how grave rebels regarded the possibility of Assad, boosted by his Shi’ite militia allies and Iran, wresting back Aleppo.

But the movement will now have to regroup. The Liwa al-Tawhid say they have appointed Abdul Aziz Salama to succeed Abdul Qadir al-Saleh as military commander.

The Syrian opposition National Coalition told AFP news agency its president had also been invited to visit Moscow at the same time, but had been unable to attend due to prior commitments.

The United States, Russia and the United Nations are trying to convene the much-postponed conference in Geneva to try to end the civil war.

Monday’s meetings follow a telephone call on Thursday between President Vladimir Putin and Syrian President Bashar al-Assad, which the Kremlin said was their first since

Putin returned to the Russian presidency in 2012.