TRIPOLI - The United Nations plans to move up to 10,000 illegal migrants from Libya next year, a senior UN official said on Tuesday, in a bid to relieve the plight of thousands stranded in deteriorating conditions in detention centers there.Libya is the main departure point for migrants fleeing poverty or war to reach Europe by boat as smugglers exploit turmoil gripping the country since the 2011 overthrow of Muammar Gaddafi.Illegal migrant arrivals in Italy have fallen by two-thirds since July from the same period last year since the UN-backed government in Tripoli, Italy's partner, cut back human smuggling at one major hub. Italy also helps in the Libyan coast guard's operations.But activists say the push has led to worsening of conditions in detention centers, where Human Rights Watch and other groups say migrants face overcrowding, abuse, lack of medical facilities and a shortage of food.The U.N. is repatriating migrants to African countries willing to take them back but it was also in talks with European countries and Canada to take in some refugees, Roberto Mignone, chief mission of the UN refugee agency, said."This week we are going to send out of Libya 350 refugees, until the end of January we will send out at least 1000," he told Reuters in an interview."In 2018 we are planning to send out of Libya between 5,000 to 10,000 refugees. We give priority to women, children, elderly, disabled, persons who suffered very seriously."A total of 44,306 had been registered as refugees and asylum seekers in Libya, he said.