Of the 8,000 asylum seekers who have lost their claim to refugee status in the Netherlands this year, 4,000 returned to their country of origin, either voluntarily or via deportation programmes, broadcaster Nos says on Thursday.

The whereabouts of the remaining 4,000 is unknown, and they may have remained in the Netherlands without papers, the broadcaster says. Nevertheless, 31% of those refused refugee status left the country voluntarily, compared with 18% in 2011.

Refugees are only sent home or deported to countries which are considered safe, such as the Balkans, Nigeria and Kosovo.

Parliament is due to debate the refugee crisis later on Thursday.

The Netherlands has a policy of evicting failed asylum seekers from refugee centres if they refuse to cooperate with their deportation. Refugee organisation Vluchtelingenwerk estimates some 5,000 would-be refugees are turned out onto the street every year.

Several hundred high profile failed asylum seekers are currently squatting or living in temporary accommodation in Amsterdam and other cities. They say they cannot return home because it is unsafe or because they don’t have proper papers.