NEW YORK - Pakistani teenager and Nobel laureate Malala Yousafzai on Tuesday told Nigerian schoolgirls who were kidnapped a year ago by Boko Haram militants they will never be forgotten and to never lose hope.

"Please know this: we will never forget you. We will always stand with you," 17-year-old Yousafzai wrote in an open letter to the missing girls. "We will not rest until you have been reunited with your families."

Yousafzai was shot in the head on a school bus in Pakistan by the Taliban in 2012 for refusing to quit school and won global acclaim for her passionate advocacy of women's right to education.

Last year, she was awarded the Nobel Peace Prize jointly with Indian children's rights activist Kailash Satyarthi.

In her letter, Yousafzai called on Nigerian authorities and the international community "to do more" to free the more than 200 schoolgirls abducted by Boko Haram Islamist militants a year ago.

Their abduction from a secondary school in Chibok in the country's Northeast last April drew international attention to the humanitarian crisis caused by attempts by the militants to establish a medieval-style caliphate in religiously