PARIS (AP) — Hundreds of migrants have fled a detention center in coastal Libya and crowded overnight around a U.N. facility, saying they were denied food for weeks.

Around 450 people left Abu Salim detention center late Tuesday. One of the migrants, as well as activists, say they were forced to beg for money from families to pay police to buy them food. Those who couldn't pay went hungry.

The migrant spoke Wednesday on condition of anonymity, fearing for his safety. They walked about 90 minutes through the city of Tripoli, according to Tarik Lamloum, a Libyan activist.

The U.N. refugee agency says the facility is already overcrowded, with about half the 800 people inside arriving informally, including many from another detention center that was hit last summer by an airstrike.