US help in Nigerian hunt

In a letter to Congress, US President Barack Obama said the personnel would stay in Chad, which borders on northeastern Nigeria, until their support "is no longer required."

"These personnel will support the operation of intelligence, surveillance and reconnaissance aircraft for missions over northern Nigeria and the surrounding area," Obama said.

The US is already carrying out reconnaissance flights, both manned and unmanned, to hunt for the girls over remote areas in Nigeria's northeast where the Islamist militant group Boko Haram is based. The Pentagon is also sharing intelligence directly with the Nigerian government.

Boko Haram militants took the girls in April from a boarding school in the town of Chibok, close to Nigeria's border with Cameroon, Niger and Chad. The girls' whereabouts are unknown.

The abduction has proved international outrage, along with criticism of the Nigerian government for what has been seen as a slow response to the incident. Until the abduction, the Nigerian authorities had also resisted any cooperation with the West in its fight against the group.

Further attacks

As the search for the girls continues, Nigerian authorities are also probing the nation's deadliest-ever bomb blast on Tuesday in the central city of Jos, which killed at least 118 and wounded dozens of others. The twin car-bomb attack on a busy marketplace and bus station has been blamed on Boko Haram.

The group is also being made responsible for three more attacks, two near Chibok and one near Lake Chad between Monday and Wednesday. The attacks reportedly left some 50 people dead.

Boko Haram, whose name means "Western education is sinful," aspires to establish an Islamic state in Nigeria, whose population is half-Christian and half-Muslim.

Its violent five-year insurgency has led to thousands of deaths.

tj/ (AFP, Reuters, AP)