Five female suicide bombers targeted the Chibok home town of Nigeria's kidnapped schoolgirls, killing nine civilians and wounding 32, witnesses said.

Soldiers are searching the north-eastern town for two other women seen with the bombers and also suspected to be strapped with explosives, according to teacher Emmanuel Cosmos.

One of three wounded soldiers died in hospital later, according to a nurse.

A man at the scene said the blasts with shrapnel zapping through the air began when soldiers stopped a young woman wearing a hijab for a routine search at the entrance to an open-air, roadside vegetable market in the north east Nigerian town. She blew herself up.

Then three women already inside the market exploded in quick succession.

Another blast occurred at a military checkpoint at the entrance to Chibok, according to witnesses and community leader Tsambo Hosea Abana. He said relatives called him in Abuja, Nigeria's capital, to tell him that his niece and uncle are among the wounded.

Residents blamed Boko Haram, the Islamic extremist group that kidnapped nearly 300 Chibok schoolgirls in April 2014. Dozens escaped but 219 remain missing. Chibok is a Christian enclave in Nigeria's predominantly Muslim north.

The plight of the girls brought Boko Haram international attention. The failure to rescue the schoolgirls contributed to the election defeat last year of former president Goodluck Jonathan.

The militants have said some of the girls have converted to Islam and threatened to sell them into slavery. It also said some have been married to its fighters.

There has been no further news of the girls, though there are reports some were carried across Nigeria's borders.

President Muhammadu Buhari has said he is willing to negotiate their release in exchange for detained militants but that his government has been unable to identify a credible leader for such talks.

Boko Haram's increasing use of girls and young women as suicide bombers has raised fears the militants are using captives as weapons.