The United Nations called on Italy on Tuesday to take back African asylum seekers among hundreds who have been forcibly returned to Libya under a new policy that has been condemned by Italian bishops and the Council of Europe.

Italy says that since last week it has returned more than 500 people to Libya on several boats under an agreement reached with Tripoli. But the UN High Commissioner for Refugees said Italy risked violating its obligations under the 1951 refugee convention by sending back to Libya refugees from Eritrea and Somalia who were seeking asylum.