Two suspected child suicide bombers blew themselves up in a market in northeast Nigeria on Sunday, witnesses said, killing three people in the second apparent attack in two days using young girls strapped with explosives.

The blasts struck around mid-afternoon at an open market selling mobile handsets in the town of Potiskum in Yobe state, which has frequently been attacked by the Sunni Muslim jihadist group Boko Haram.

A trader at the market, Sani Abdu Potiskum, said the bombers were about 10 years old. "I saw their dead bodies. They are two young girls of about 10 years of age ... you only see the plaited hair and part of the upper torso," the trader said.

A source at the Potiskum general hospital said three people had been killed, excluding the bombers, while 46 were wounded.

Students slain

The town was hit by a suicide bomber in November when at least 48 people, mainly students, were killed during a school assembly. On Saturday, a bomb exploded at a police station in Potiskum.

Sunday's explosions came a day after a bomb strapped to a girl aged around 10 exploded in a busy market place in the Nigerian city of Maiduguri, killing at least 16 people and injuring more than 20, security sources said.

In New York, the executive director for UNICEF said the horrific images coming out of Nigeria should be searing the consciences of the world.

“Some 2,000 innocent children, women and elderly reportedly massacred in Baga," Anthony Lake said. "A young girl sent to her death with a bomb strapped to her chest in Maiduguri and, lest we forget, more than 200 girls stolen from their families, still lost.

“Words alone can neither express our outrage nor ease the agony of all those suffering from the constant violence in northern Nigeria. “But these images of recent days and all they imply for the future of Nigeria should galvanize effective action. For this cannot go on.”

Headache for president

Boko Haram has been waging a five year insurgency to establish an Islamic state in the northeast of the country and the army's inability to quash the movement is a headache for President Goodluck Jonathan, who is seeking re-election in February.

Last year more than 10,000 people died in the violence, according to an estimate by the Council on Foreign Relations

The military lost ground in worst-hit Borno state last weekend after insurgents took over the town of Baga and nearby army base, killing more than 100 people and forcing thousands to flee. The defence headquarters said on Saturday the army was regrouping to retake the area.

In the city of Jos in Plateau state, Jonathan's campaign team was hit by two days of violence.

The driver of a campaign vehicle was killed on Sunday by youths who also set fire to a police station, police spokesman Abu Sunday Emmanuel said. On Saturday, two other campaign vehicles were burned.

"The youths were chanting no PDP, no to Jonathan Badluck," a witness said, referring to the ruling People's Democratic Party.

PDP spokesman Olisa Metuh said in an emailed statement that the government "decried last Saturday's unprovoked attack on President Goodluck Jonathan's campaign vehicles in Jos."