Three children were among at least 11 civilians killed on  Wednesday when a Syrian government aircraft dropped a barrel bomb on a rebel-held neighborhood of Aleppo, a monitoring group said.

The air raid came a day after rebel mortar fire on government-held areas of the northern city killed 38 people, including at least 18 children, drawing U.N. condemnation.

A market in fake Syrian passports has sprung up, particularly in Turkey, to help migrants and refugees enter the EU, the head of Europe's border agency Frontex said on Tuesday.

"There are people who are in Turkey now who buy fake Syrian passports because they know Syrians get the right to asylum in all the member states of the European Union," Fabrice Leggeri told French radio station Europe 1.

At least 37 civilians were killed Wednesday in Syrian government air strikes near Damascus, while at least 13 people died as rebels fired a barrage of rockets into the capital, a monitor said.

The Syrian Observatory for Human Rights said at least four children were among the dead in regime strikes on the rebel-held Eastern Ghouta region, where some 120 people were also wounded.

Islamic State group fighters attacked a town near their de facto Syrian capital Monday in a bid to recapture it from Kurdish and Arab rebel forces, a Kurdish spokesman said.

"IS launched a large-scale offensive at dawn... and managed to enter Ain Issa," said Redur Khalil, a spokesman for the Kurdish People's Protection Units.

Kurdish fighters ousted the Islamic State group from the Syrian border town of Kobane on Saturday, two days after the jihadists had seized several neighborhoods, a monitor and activists said.

IS's bloody attack on the town had left at least 174 civilians dead as well as 70 combatants, the Syrian Observatory for Human Rights said.

Clashes between the Islamic State jihadist group and government troops in the northeast Syrian city of Hasakeh have displaced an estimated 60,000 people, a U.N. agency said on Thursday.

The UN office for the Coordination of Humanitarian affairs (OCHA) said at least 50,000 people had been displaced within Hasakeh while another 10,000 had fled north towards the town of Amuda.

One person was killed and three wounded on Sunday in a suicide bomb attack on the Kurdish city of Qamishli in northeastern Syria, the official news agency SANA reported.

"A terrorist detonated his explosive belt near the Hadaya hotel in the center of Qamishli, killing one person and seriously injuring three others," the news agency said.

The army on Monday arrested several Syrians in the eastern Bekaa region on terrorism charges.

"Army intelligence agents arrested a terrorist group comprising 4 Syrians in Jib Janine and Kamid el-Loz in western Bekaa," LBCI television reported in the evening.

Turkish President Recep Tayyip Erdogan has threatened an opposition daily which published footage allegedly showing trucks belonging to the state intelligence service carrying weapons to rebels in Syria, vowing it will pay a "heavy price".

"The slander against the National Intelligence Organization and the illegitimate operation (against MIT trucks) is an espionage activity at one point," Erdogan told state-run TRT television late Sunday. "This newspaper was also involved in this espionage activity."

At least 16 members of the Syrian Kurdish security forces were killed Wednesday in an Islamic State group attack on a base in the northeastern province of Hasakeh, a monitor said.

"There was a large explosion at dawn today in Hasakeh city caused by an Islamic State car bomb attack on a base belonging to the Kurdish internal security forces," the Syrian Observatory for Human Rights said.