United Nations Secretary-General Antonio Guterres on Friday welcomed the release of abducted children in Nigeria.

Through a statement attributable to his deputy spokesperson Farhan Haq, the UN chief welcomed the release on Dec. 17 of some of the children who had been abducted from a secondary school in Katsina State, Nigeria, on Dec. 11.

Guterres commended “the swift action” taken by the Nigerian authorities to rescue the children and called for “the immediate and unconditional release” of those who remain abducted, said the statement.

The secretary-general stressed the importance that the released children and their families are provided with “the necessary health and psychosocial support.”

The secretary-general called for increased efforts to safeguard schools and educational facilities in the country and reiterated the solidarity and commitment of the United Nations to supporting the government and people of Nigeria in their fight against terrorism, violent extremism and organized crime.

More than 300 schoolboys were reportedly missing for nearly a week, after an attack on the Government Science Secondary School Kankara in Katsina State. The Nigerian military rescued 344 of them late on Thursday.