TRIPOLI, Nov. 1 (Xinhua) -- The International Organization for Migration (IOM) announced late Wednesday that 139 illegal immigrants were voluntarily deported from Libya to Nigeria.

"Another group of migrants returned home to Nigeria from Libya yesterday. Among the 139 migrants, there were five pregnant women and seven unaccompanied children, as well as four people with medical conditions," IOM said in a statement later on Wednesday.

The return was done with the support of the European Union Trust Fund, the statement said.

The IOM is running a voluntary return program with an aim to arrange the return of illegal immigrants stranded in Libya to their countries of origin.

Migrant shelters in Libya are crowded with thousands of migrants who have been rescued at sea or arrested by Libyan security services.

Libya has become a preferred point of departure for illegal immigrants hoping to cross the Mediterranean Sea into Europe due to insecurity and chaos in the North African country following the 2011 uprising that toppled former leader Muammar Gaddafi.