Russia says the formation of the so-called Army of Aleppo in the east of the Syrian city is an attempt to disguise and shield the al-Nusra Front terrorist group.

“I do not rule out that this is just another attempt to rebrand al-Nusra Front and shield it from righteous retaliation,” Russian Foreign Minister Sergei Lavrov said in Rome on Friday.

Lavrov stressed that nearly all the militant groups in the eastern part of the flashpoint Syrian city, where the “Army of Aleppo” was recently formed, are under the control of al-Nusra Front.

“As I have already mentioned, according to our intelligence,… practically all armed opposition groups in eastern Aleppo report to al-Nusra Front. Nusra has some 1,500 militants there, while other groups under its command have up to 6,000 militants,” he said.

Al-Nusra Front is an affiliate of al-Qaeda that has recently renamed itself Jabhat Fateh al-Sham and has claimed to have broken up with al-Qaeda in what has largely been interpreted as a decoy attempt.

Russia has long been pressing for the designation of al-Nusra as a terrorist group at the United Nations Security Council. Such attempts have, however, been hindered by the United States.

Lavrov also said his country had supported  an initiative by UN Special Envoy for Syria Staffan de Mistura on the exit of militants from eastern Aleppo.

“De Mistura proposed allowing all terrorists to leave eastern Aleppo, we, despite the idea’s controversy, supported it and were ready to cooperate with it,” he said, adding the proposal “was blocked by those who, we are convinced, are interested in eastern Aleppo remaining under the control of terrorists.” He did not elaborate.

The Syrian government holds and defends the city’s western side and has been purging its east of militants.

Meanwhile, a monitoring group said on Friday that Syrian troops had taken control of half of the militant-held areas in eastern Aleppo.

Rami Abdel-Rahman, the head of the so-called Syrian Observatory for Human Rights, said the government forces “consolidated their control” over two eastern districts on Friday, adding they are now “comfortably in control of half” of the militant-controlled areas in Aleppo’s east.

He added the Syrian forces were advancing toward the recapture of the rest of the areas under the militants’ control in the east of the city.

The Russian Defense Ministry had already announced on Tuesday that the Syrian army had extended its control to half of those areas.

Russia has been offering military support to the Syrian government.

Elsewhere in his Friday remarks, Lavrov blamed the foreign-backed opposition for the stall of the intra-Syrian peace talks for more than six months, saying they “put forward ultimatums in the form of an absolute precondition to oust President [Bashar] Assad.”

The conflict in Syria, which flared up in March 2011, has claimed the lives of more than 400,000 people, according to an estimate by UN Special Envoy for Syria Staffan de Mistura.