Video footage posted online claims to show the aftermath, with people carrying away the wounded and a wide area reduced to rubble.

Activists say families are buried under the rubble in one neighbourhood.

Meanwhile, opposition politicians say they have agreed to form a government for rebel-held areas.

Umbrella group the Syrian National Coalition, meeting in Cairo, said it would meet again in Istanbul on 2 March to name a prime minister.

The UN estimates that about 70,000 people have died since the uprising against President Bashar al-Assad's regime began in March 2011.

Voice of Russia, BBC