An air strike has killed 20 people, including children, in the northern Syrian city of Aleppo, according to Syrian activist groups.

The British Syrian Observatory for Human Rights and the Aleppo Media Center said that the bombing happened in the city's al-Sukkari neighbourhood.

The Observatory estimates that approximately 2,000 people have been killed by Syrian government airstrikes this year.

Syrian President Bashar al-Assad's forces have continued to drop barrel bombs over rebel areas of Aleppo, the country's biggest city, as the civil war rages into its fourth year.

Earlier this month, Assad won a third seven-year presidential term with 88.7% of the votes.

In spite of the violent civil war, he has retained popular support among Syria's population, especially Christians and Alawites, as Islamic militant groups, such as the Islamic State of Iraq and the Levant (Isis) and the Nusra Front, are viewed as brutal alternatives.

Elsewhere, Syrian government forces recaptured the coastal village of Kasab, the heartland of Assad's Alawite minority sect, after rebel forces withdrew.

Syrian state news agency SANA said that Assad's forces had "restored stability and security" in the village.

The UN has estimated that over 2.8 million Syrian refugees have fled into neighbouring countries, and more than 160,000 have died since the civil war began in 2011.