The UN health agency says 443 people have died and 2,110 have been wounded in violence in Libya's capital since the head of the self-styled Libyan National Army launched an offensive against Tripoli last month.

With the number of people displaced by fighting approaching 60,000, the World Health Organization said in a tweet Wednesday that it is working to co-ordinate ongoing health services for them.

UN deputy spokesman Farhan Haq said Wednesday the UN is very concerned about reports that airstrikes a day earlier hit a migrant detention centre in Tajoura in eastern Tripoli, reportedly injuring two migrants.

He told reporters the UN mission in Libya "is also deeply concerned about increased cases of arbitrary arrest and abduction of officials, activists and journalists" and is calling for their immediate release.