Tripoli - Some 1,000 people have been killed since Libyan general Khalifa Haftar launched a push three months ago to capture Tripoli, the UN said Friday, including 53 detained migrants who died in a devastating air strike.

Haftar’s Libyan National Army, which holds eastern Libya and much of the country’s south, launched an offensive in early April to wrestle the capital from forces loyal to the Government of National Accord (GNA).

Air strikes and ground fighting have since left nearly 1,000 people dead and some 5,000 wounded, the UN’s World Health Organisation said, without specifying the breakdown between civilians and fighters.

The fighting has forced more than 100,000 people to flee their homes in a country mired by a bloody power struggle between militias since a NATO-backed uprising that toppled and killed dictator Muammar Gaddafi in 2011.

Among the dead are 53 migrants killed Tuesday night in an air raid on a detention centre in the Tripoli suburb of Tajoura, held by the GNA, which accused Haftar’s forces of carrying out the strike.

A Geneva-based spokesman for the International Organisation for Migration said six children were among the migrants killed.

Joel Millman said that “350 migrants, including 20 women and four children” were still detained at the centre, one of five air hangers hit in the raid.

An initial lightning assault in early April saw the LNA steam towards the capital. But they have since been bogged down on its southern outskirts, where frontlines have been frozen for months.

The GNA forces launched a surprise counter-attack late last month, seizing the strategic town of Gharyan, the main supply base for Haftar’s offensive.

After the setback, Haftar’s forces threatened to intensify strikes against their rivals.

Both sides have launched daily air raids throughout the fighting and each lost several planes.

Troops loyal to Haftar said late Thursday they had downed a GNA jet near the town of Tarhuna, used by the LNA as a rear base some 80 kilometres (50 miles) southeast of Tripoli

A GNA spokesman said they had lost contact with the L39 Albatros, which had been on a combat mission south of the capital, without providing further details.