Syria Aleppo Bomb
A Civil Defence member runs towards a damaged site after what activists said were explosive barrels thrown by forces loyal to Syria's president Bashar Al-Assad in Al-Shaar neighbourhood of Aleppo.Reuters

Thirty-three people are believed to have been killed in a government air strike on a market in the northern Syrian city of Aleppo.

The attack took place in the northern Halak district, according to the Syrian Observatory for Human Rights.

Unicef condemned the "latest wave of indiscriminate attacks perpetrated against schools and other civilian targets" across the wartorn country.

"These attacks appear to be escalating in complete disregard of all the calls that have been made to stop this insane cycle of violence, and to avoid similar breaches of international law," the charity said.

This week, Assad's military forces targeted a school with an airstrike which killed 18 people. Ten were children.

Aleppo has been devastated by fighting between the government and rebel forces since 2012.

Bashar al-Assad is to seek a third seven-year term as president at elections on 3 June.

He will run against six candidates and despite the civil war is expected to win. His family has ruled the country for four decades.

The election has been criticised by opponents as a farce that does not represent Syrians. Of a population of 16 million, more than 2.5 million have fled the country and six million have been displaced.

Approximately 150,000 people have died in the civil war and more than three million people denied vital medical aid.