Dozens of bodies presumed to be African migrants have washed ashore in the western Libyan city of Zawiya, humanitarian officials said.

At least 74 bodies were found on the beach in Zawiya but the circumstances of their drowning remain a mystery, said Mohammed al-Misrati, a spokesman for Libya's Red Crescent organisation.

The bodies washed ashore overnight but there was apparently no sign of a wrecked boat or vessel they had been on.

The aid agency posted on its Twitter account photographs of dozens of bodies in black and white body bags, lined up along the shore.

Mr al-Misrati said local authorities are taking the bodies to a cemetery for unidentified people in the capital Tripoli.

The bodies washed ashore overnight but there was apparently no sign of a wrecked boat.

Migrant deaths have risen to record levels along the Libya-Italy smuggling route across the Mediterranean Sea.

Last week, Fabrice Leggeri, director of the European Border and Coast Guard Agency, said the route saw record numbers of migrant drownings last year.

He said the total for the central Mediterranean route was 4,579 last year, which might still be much less than the true figure. That compares with 2,869 deaths in 2015 and 3,161 in 2014.

There is little sign of the surge is abating, even during winter. There were 228 recorded deaths in January, by far the biggest monthly toll in recent years.

Mr Leggeri blamed the use of small dinghies and other poor vessels for the high death rate.

The turmoil engulfing Libya has become a death trap for thousands of migrants, most of them from sub-Saharan African countries, seeking to escape poverty and find a better life in Europe.

Libya, divided under competing governments, is run by militias, many of which profit from smuggling and human trafficking.

Rights groups have documented migrants' horror journeys involving torture, rape, and forced labour inside Libya.

The country sank into lawlessness after the 2011 uprising that turned into a full-blown civil war which led to the toppling and killing of long-time dictator Muammar Gaddafi.

Since then, human trafficking has thrived amid the chaos.

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