Separate air raids in northern Syria by regime aircraft and warplanes of the US-led international coalition killed at least 25 civilians on Friday, a monitoring group said.

President Bashar al-Assad's air force attacked a crowded market in Aleppo city's rebel-held district of Tariq al-Bab, killing 11 people, the Syrian Observatory for Human Rights reported.

Another five people were killed in an air raid on the southern rebel-held neighbourhood of Sheikh Said, it said.

The Britain-based monitor said rebel bombardment of government-held districts killed two civilians in the city that has been divided since July 2012.

It also said a coalition raid on the northern city of Manbij, where US-backed fighters are battling the Islamic State jihadist group, killed two women and their seven children.

Kurdish and Syrian Arab fighters have been advancing on Manbij, an important waypoint between the Turkish border and Raqa, the jihadists' de facto capital.

The conflict in Syria has killed more than 280,000 people over the past five years and displaced millions from their homes.

Two 'senior' IS military leaders killed in Iraq strike: Pentagon
Washington (AFP) July 1, 2016 - A coalition air strike near the Islamic State bastion of Mosul in Iraq has killed two of the jihadist group's senior military leaders, the Pentagon said Friday.

"Coalition forces conducted an air strike against two ISIL senior military commanders on June 25 near Mosul, Iraq, resulting in their deaths," Pentagon press secretary Peter Cook said in a statement, using an acronym for the IS group.

"The precision strike killed Basim Muhammad Ahmad Sultan al-Bajari, ISIL's deputy minister of war, and Hatim Talib al-Hamduni, an ISIL military commander in Mosul."

Cook said al-Bajari was a former Al-Qaeda member who joined the IS group and oversaw the June 2014 offensive to capture Mosul.

He "also led the ISIL Jaysh al-Dabiq battalion known for using vehicle-borne IEDs (homemade bombs), suicide bombers and mustard gas in its attacks."

Al-Hamduni was a military commander in Mosul and the head of military police in the region, Cook said.

Mosul is Iraq's second-largest city and became the IS group's de facto Iraq capital.

Iraqi security forces have in recent weeks made significant progress against the IS group, including the recapture of the city of Fallujah this month.

Attention is now shifting to Mosul, where a battle to liberate the city is expected to unfold in the coming months.

"Removing these terrorist leaders from the battlefield shapes the environment for Iraqi forces to ultimately liberate Mosul with support from the international coalition," Cook said.