At least 12 people were said to have been killed by airstrikes in Syria's northern province of Aleppo, a monitor group reported on Tuesday.

Warplanes, believed to be Russians, carried out an airstrike on the Islamic State (IS)-held town of Maskaneh in the eastern countryside of Aleppo on Tuesday -- targeting a marketplace, according to Syrian Observatory for Human Rights, Xinhua reported.

The number of deaths is expected to rise due to the high number of critically wounded people, the Britain-based watchdog group added.

Other activists placed the death toll in Maskaneh at 30.

Opposition activists often accuse the Russian air force, which has been striking IS positions for over two months, of targeting civilian areas, a claim totally denied by Moscow.

Meanwhile, the Observatory said clashes continued on Tuesday in the southern countryside of Aleppo, where the army backed by the Russian air strikes has been trying to advance against an array of jihadi groups.

On the other hand, Iran Foreign Ministry spokesperson Hossein Jaber Ansari said on Tuesday that Iran has assisted Syria with military advisors in its fight against terrorism and will continue to do so.

Iran has followed a straight and clear policy about the Syrian crisis, fighting terrorism and has never slacked about it, Ansari said in his weekly press briefing.

Asked whether Syria has demanded Iran to send military forces to Syria, he said that, Syria has made no request in this regard and in case of any request Iran will consider it within the framework of its principles.

In October, Iranian Deputy Foreign Minister for Arab and African Affairs Hossein Amir-Abdollahian said that Iran had increased the number of its military advisers to the Syrian government in the fight against terrorists.

The Iranian foreign ministry official denied that Iran had sent ground forces to Syria to fight along with the Russian air forces against the militants.

Iran has emerged as a staunch regional ally of Syria in the country's long-lasting conflict.