An Algerian military plane has crashed near the capital killing 257 people on board, officials say.

The aircraft came down just after taking off from Boufarik military airport, west of Algiers.

An investigation into the cause is under way. Algerian President Abdelaziz Bouteflika has declared three days of national mourning.

Most of the dead are army personnel and their families, the defence ministry says. Ten crew members also died.

A senior member of the ruling FLN party said 26 members of the Polisario Front, an Algerian-backed separatist group in Western Sahara, were also among the dead.

Morocco annexed Western Sahara after the Spanish colonial power withdrew in 1975. The Polisario Front has been fighting for independence since 1976 and has a government-in exile-in Algeria.

The plane, an Ilyushin Il-76, was travelling to Bechar in the south-west of the country. It was scheduled to make a stop in the town of Tindouf, close to the borders with Morocco and the disputed Western Sahara territory.

This is not the first major plane disaster in Algeria. It is the second-deadliest plane crash since 2003

Wednesday’s plane crash is the deadliest in the world since July 2014, when all 298 people on board Malaysian Airlines flight MH17 died when it was shot down over eastern Ukraine.

Four years ago a plane carrying military personnel and family members crashed in Algeria, killing 77 people.

Story was originally published by BBC News