US First Lady Michelle Obama has said the mass kidnap of Nigerian schoolgirls is part of a wider pattern of threats and intimidation facing girls around the world who pursue an education. She said she and her husband Barack Obama were "outraged and heartbroken" over the abduction on 14 April of more than 200 girls from their school.
She was speaking instead of her husband in the weekly presidential address.
Recall that Boko Haram has claimed responsibility for the abductions.
'Call to action'
Mrs Obama, who was speaking ahead of Mother's Day in the US on Sunday, said the girls reminded her and her husband of their own daughters.
"What happened in Nigeria was not an isolated incident. It's a story we see every day as girls around the world risk their lives to pursue their ambitions," she said.
She cited the Pakistani schoolgirl and campaigner Malala Yousafzai, who was shot and wounded by the Taliban for speaking out for girls' education.
It is unusual for a US first lady to make outspoken foreign policy remarks, but Mrs Obama has campaigned for the girls' release.
Michelle Obama has often appeared alongside her husband during the weekly address, but this is the first time she has delivered the speech alone. Earlier this week, she tweeted a picture of herself in the White House holding a sign with the message "#BringBackOurGirls".
The UN Security Council expressed outrage over the abductions, saying it would consider "appropriate measures" against Boko Haram. The US is seeking to have UN sanctions imposed on the group.
US and British experts are in Nigeria to assist with rescue efforts. A senior US official said Washington was also considering a Nigerian request for surveillance aircraft.
British High Commissioner Andrew Pocock said drones could help gather intelligence but urged caution.