LAGOS, Feb. 26 (Xinhua) -- The United Nations Children's Fund (UNICEF) representative in Nigeria has expressed concerns about and strongly condemns continuous terror attacks on schoolchildren in the west African country.

Early Friday, an unknown number of students were abducted by gunmen who stormed an all-girls school in Nigeria's northwestern state of Zamfara, about a week after 42 people, including 27 students, were taken away by gunmen who attacked a boarding school in Niger state in north-central Nigeria.

"We are angered and saddened and by yet another brutal attack on schoolchildren in Nigeria," said Peter Hawkins, UNICEF representative in Nigeria, in a statement.

"This is a gross violation of children's rights and a horrific experience for children to go through - one which could have long-lasting effects on their mental health and well-being," the UNICEF chief added.

"We utterly condemn the attack and call on those responsible to release the girls immediately and for the government to take steps to ensure their safe release and the safety of all other schoolchildren in Nigeria," said Hawkins.

He said children should feel safe at home and at school at all times and parents should not need to worry for the safety of their children when they send them off to school in the morning.

UNICEF acknowledges efforts being made by the government of Nigeria to secure the release of kidnapped school children in Nigeria and calls on the government and all concerned to make schools safe in Nigeria, Hawkins said.

"UNICEF is working with partners to confirm the exact number of kidnapped students," he said.

The Zamfara state government has confirmed the abduction of female students of Government Girls Secondary School at Jangebe, a town in the state's Talata-Mafara area, by hundreds of gunmen at about 2:00 a.m. local time.

A security source told Xinhua that over 300 students are yet to be accounted for.

The latest abduction came about a week after gunmen struck the Government Secondary School at Kagara, a town in the north-central state of Niger, abducting 27 school pupils, three school staff, and 12 family members of the school staff.

They have yet to be rescued as of Friday.

The northern region of the most populous African country has witnessed a series of armed attacks in recent months, with hundreds killed and many others abducted.