At least 43 people have been killed and 190 others injured by opposition rocket fire in the Syrian city of Aleppo, a monitoring group said.

Up to 300 rockets were fired by rebel fighters on government controlled neighbourhoods in Aleppo, Syria's second largest city, the UK-based Syrian Observatory for Human Rights reported on Tuesday.

The death toll was expected to rise as many sustained critical injuries, the observatory said, adding that at least 12 of those killed were children.

In the suburbs of Aleppo, opposition fighters clashed with the Islamic State of Iraq and the Levant (ISIL) group for control of supply lines.

In Homs province, government jets in the past five days bombed the city of Palmyra, a local activist told Al Jazeera.

"For the past few days we have been attacked by air strikes and barrel bombs. We could not determine a final death toll yet but at least four people have been killed so far. The situation here is devastating," the activist said.

The observatory said that the government dropped barrel bombs on the provinces of Deraa and Hama, killing 14 and 15 respectively.

Several rockets targeted the capital Damascus, including the area of the Russian Embassy. One person was killed in those attacks.

Kurdish forces advance

Clashes continued between Syrian Kurdish fighters and ISIL fighters in the town of Tal Abyad on Tuesday morning.

Tal Abyad lies on a major supply route to Raqqa province and is bordering Turkey. Kurdish fighters said they are now in full control of the town.

At least 40 ISIL fighters were reported killed in US-led air strikes as they fled Tal Abyad.

The Kurdish advance has caused the displacement of more than 16,000 people, who have fled to Turkey in the past two weeks.

Leo Dobbs of the UNHCR, told Al Jazeera that Turkish authorities confirmed to the UN that 23,135 refugees have arrived into Turkey since June 3.

"Most were Syrians but 2,183 are Iraqis from Mosul, Ramadi and Fallujah," Dobbs said.

Kurdish fighters and Syrian rebels began their main advance on the town on June 11, backed by air strikes from the US-led coalition.

UN envoy in Syria

The UN peace envoy Staffan de Mistura landed in Damascus on Monday, after an invitation by the government to visit the country, according to a UN spokesman.

De Mistura is expected to submit a report to the Secretary-General regarding the implementation of the Geneva Communique.

The Special Envoy also plans to discuss the current humanitarian situation in Syria and ways to increase access to besieged and conflict-affected communities, a UN news release said.

In his discussions, De Mistura plans to convey once again to Syrian officials his deep conviction that no solution to the Syrian conflict can be imposed by force and that an inclusive and Syrian-led and owned political settlement is urgently needed.

During Syria's five year conflict, at least 230,000 people have been killed while millions of others have been displaced - including four million Syrian refugees who fled to neighbouring countries.