By Kieran Guilbert

DAKAR, Feb 24 (Thomson Reuters Foundation) - Many refugees and migrants in Libya are not seeking needed healthcare as they fear being caught up in conflict between warring factions or detained, robbed or kidnapped at official and fake checkpoints, an aid agency said on Wednesday.

Most of those who arrive in Libya lack identity documents - which they are required to show at checkpoints to get to health facilities - and are afraid of being sent to detention centres as a result, said the International Medical Corps (IMC).

Others have been trapped by fighting between armed groups supporting two rival governments, and Islamic State militants, or threatened by gunmen posing as security officials at fake checkpoints, according to the medical aid organisation.

"Life in Libya is so hard for migrants, asylum seekers and refugees... they face a lot of trouble and are terrified to travel," said IMC Libya security manager Fabrice Faicel Ilahi.

"Armed men running fake checkpoints are benefiting from a lack of central authority and are subjecting these vulnerable people to extortion, robbery, abduction and even forced labour."

There are some quarter of a million refugees and migrants in the North African country of 6.3 million people.

Many of them have fled Syria's five-year-old civil war or travelled north through Africa's Sahel region in the hope of crossing the Mediterranean to start new lives in Europe.

Syrian asylum seeker Saad Elmasri, who arrived in Libya in 2011, said his family suffered verbal abuse from Libyan soldiers in the streets because his wife's passport had expired.

"We struggle to access healthcare due to the expired passport... we never think about moving during the night because of robberies and other acts at fake checkpoints," the 60-year-old said by phone from the capital, Tripoli.

The IMC is carrying out medical consultations, providing healthcare for those held in detention centres, and distributing health kits which include medicine, blankets and heaters.

Libya could run out of life-saving medicine within a month, which would affect the lives of one million people, the United Nations humanitarian coordinator for Libya said on Tuesday.

The violence has taken a heavy toll on health facilities, with only two out of a dozen hospitals in the eastern city of Benghazi currently functioning, Ali Al-Za'tari said.

Around 2.4 million people in Libya - four in 10 of the population - need humanitarian aid, according to the U.N. Office for the Coordination of Humanitarian Affairs (OCHA).

Libya's eastern parliament, which is internationally backed but opposed by a rival government in Tripoli, rejected an initial unity government last month, while Islamist fighters have exploited the security vacuum to expand their presence. (Reporting By Kieran Guilbert, editing by Tim Pearce. Please credit the Thomson Reuters Foundation, the charitable arm of Thomson Reuters, that covers humanitarian news, women's rights, trafficking, corruption and climate change. Visit news.trust.org)