UN shuts refugee centre in Libya's capital as truce crumbles

* Tripoli subjected to military offensive since April

* Truce brokered on Jan. 12 has not stopped clashes

* UN says foreign powers still violating arms embargo

By Aidan Lewis and Michelle Nichols

CAIRO/NEW YORK Jan 30 (Reuters) - The United Nations said on Thursday it was suspending operations at a refugee centre in Libya's capital because it could become a target while the U.N. envoy said a truce brokered by Russia and Turkey was holding "only in name".

Artillery exchanges in Tripoli have significantly increased in recent days, U.N. Libya envoy Ghassan Salame told the Security Council in a briefing, causing an increase in civilian casualties due to indiscriminate shelling.

Since Jan. 12, when forces aligned with Tripoli's internationally recognised government and eastern based rivals led by Khalifa Haftar conditionally agreed to a truce, more than 110 violations had been recorded, Salame said.

Libya's conflict has escalated since Haftar launched an offensive on Tripoli in April, upending U.N.-led peace plans. International powers have supplied arms and air power, though there has been a lull in air strikes since Russia and Turkey called for a truce starting Jan. 12, and international powers met in Berlin on Jan. 19 trying to broker a ceasefire.

Haftar has received support from the United Arab Emirates, Jordan, Russia and Egypt, while Turkey has recently stepped up its backing for the Tripoli government.

U.S. Ambassador Kelly Craft told the Security Council that "regrettably the promise of the Berlin conference is already under threat". It was "past time" for those violating an arms embargo "to face real consequences", she warned, without giving details.

The 15-member U.N. Security Council has been negotiating a British-drafted resolution to endorse the outcomes of the Berlin conference, but it was not immediately clear when the text could be put to a vote.

The U.N. says arms and fighters have continued to pour into Libya despite pledges in Berlin to uphold the arms embargo, while clashes have picked up on the ground with at least 18 civilians killed and three wounded in and around Tripoli since Jan. 6.

"With recent developments on the ground, I regret to report that the truce holds only in name," Salame said.

MILITARY EXERCISES

The closure of the centre for refugees and asylum seekers in central Tripoli may further restrict protection for migrants frequently subjected to abuse including torture and forced labour, both in and out of detention.

The UNHCR Gathering and Departure Facility (GDF), which housed nearly 1,000 people, had been plagued with problems, reflecting the difficulties for international agencies working in a city controlled by armed groups.

"Unfortunately UNHCR was left with no choice but to suspend work at the (GDF) after learning that training exercises, involving police and military personnel, are taking place just a few metres away from units housing asylum seekers and refugees," Jean-Paul Cavalieri, UNHCR's Libya head, said in a statement.

"We fear that the entire area could become a military target, further endangering the lives of refugees, asylum seekers, and other civilians."

Libya's western coast has been one of the main departure points for migrants attempting dangerous sea crossings to Europe, though the number of departures has dropped sharply since mid-2017.

The country has a migrant population numbering hundreds of thousands, and several thousand are held in detention centres in or near Tripoli that have been left unguarded or hit by artillery or air strikes amid the fighting.

In July, an air strike hit a detention centre in Tripoli's Tajoura district that was located in the same complex as an armed group's vehicle repair workshop, killing at least 53 migrants.

A U.N. report issued this week repeated previous findings that the air strike was likely carried out by a foreign aircraft, but failed to name the state. (Writing by Aidan Lewis; Editing by Hugh Lawson)