A human rights group says 20 people in Syria, including women and children, have been killed in airstrikes carried out by government troops against opposition forces.

The Britain-based Syrian Observatory for Human Rights says Syrian President Bashar al-Assad's forces and the Russian military launched fierce attacks on towns and villages in Idlib province on Tuesday.

The province in northwestern Syria is the country's last anti-government stronghold.

The Observatory says so-called "barrel bombs" were used in the attacks.
The United Nations condemns the use of such weapons, as they can cause indiscriminate damage over wide areas.

Russia backs the Assad administration. Turkey supports the anti-government forces. 

The two countries set up a demilitarized zone in Idlib province and its surrounding areas in October 2018.

But the ceasefire has effectively collapsed, and that has led to the resumption of fierce airstrikes in the area since the end of April.

Attacks have reportedly been carried out on schools, markets and medical facilities, killing at least 1,294 civilians in the past seven months.

NHK