By Ahmed Elumami

TRIPOLI, July 31 (Reuters) - More than 120 bodies of migrants who died trying to cross the Mediterranean to Europe have washed up around Sabratha in western Libya this month, the city's mayor said on Sunday.

Hussein Thwadi said bodies had washed up on a daily basis, with 53 found on a single day last week.

Libya is a common departure point for migrants seeking to travel to Europe by boat, many of them fleeing violence, repression or poverty in sub-Saharan Africa.

Political turmoil and armed conflict in Libya have given smugglers the space to work with impunity, running trafficking networks that bring migrants across the Sahara desert to the coast.

Of more than 3,000 migrants known to have died trying to cross the Mediterranean this year, about three out of four perished trying to reach Italy from North Africa, mainly Libya, according to the International Organization for Migration (IOM).

Nearly 90,000 migrants had crossed the central Mediterranean to Italy as of this week, the IOM said, a 14 percent increase on the previous year.

As the number of attempted crossings from Libya picked up in the spring with the arrival of calmer weather, many of the boats have been leaving from the coastline near Sabratha.

"The whole coast of Sabratha is open," Thwadi told Reuters by phone. "There are patrols but they do not have enough capacity to tackle this crisis."

"Illegal migration existed before, but with insecurity and the lack of state authorities the crisis has become worse and worse."

Thwadi said most of the migrants whose bodies washed up this month were from sub-Saharan African states, though there were also 23 Tunisians. Red Crescent volunteers and local officials have been removing them for burial in a cemetery for unidentified bodies in Sabratha, he said.

A U.N.-backed government that has been trying to establish itself in Tripoli since March says tackling migration is among its priorities.

But the government is struggling to manage complex security and economic challenges, and still faces political opposition on the ground.

Thwadi said he had raised the issue with the new government's leadership but had not yet received any concrete response. (Writing by Aidan Lewis; Editing by Susan Fenton)