Kano (Nigeria) (AFP) - Two girls, thought to be only seven or eight years old, conducted a double suicide attack in a northeastern Nigerian market Sunday, killing one person and wounding 18, officials said.

The attack in Maiduguri was not immediately claimed by Boko Haram but bore the hallmarks of the jihadist group which often uses women or girls in such operations -- especially in Borno state -- the epicentre of their insurgency.

Borno state governor Kashim Shettima confirmed the toll to journalists while visiting victims in hospital.

The girls were "seven or eight", a militia member in Maiduguri, the capital of Borno, Abdulkarim Jabo, told AFP, recalling that he saw the attackers immediately before the first explosion.

"They got out of a rickshaw and walked right in front of me without showing the slightest sign of emotion," he said.

"I tried to speak with one of them, in Hausa and in English, but she didn't answer. I thought they were looking for their mother.

"She headed toward the poultry sellers, and then detonated her explosives belt."

Governor Shettima said he would meet security agents, market officials and civilian vigilantes -- who are assisting the military -- to try and strengthen security at market places.

The second explosion was apparently triggered slightly later as bystanders were helping the wounded.

"We removed 17 people with different degrees of injuries," said Bello Dambatta of the local emergency management agency.

- 'Mutilated bodies' -

"The mutilated bodies of the two suicide bombers were also evacuated."

Boko Haram jihadists have laid waste to northeast Nigeria since they took up arms against the government in 2009.

They are seeking to impose a hardline Islamic legal system on the country's mainly-Muslim north.

At least 20,000 people have been killed and more than two-and-a-half million more displaced by the unrest.

But the Nigerian military's campaign against the jihadists is increasingly bogged down as it confronts suicide attacks, looting and indiscriminate slaughter.

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Rights groups say thousands of women and girls have been abducted by the group. In the most infamous incident more than 200 schoolgirls were taken from the remote town of Chibok in 2014.

The jihadists have used abducted females as sex slaves and human bombs, while boys are enlisted to fight.

Northeast Nigeria has been buffeted in recent weeks by a string of devastating attacks.

On Friday at least 45 people died and 33 others were wounded in another double suicide attack carried out by female bombers, at a marketplace in the town of Madagali.

In October another set of female suicide bombers killed 17 people at a station near a camp for internally displaced persons.

In February 2015, Boko Haram used an eight-year-old to carry out a suicide attack in Potiskum, in Yobe state, and a 10- and 18-year-old pair were involved in a failed July 2014 attack in Funtua, in northwestern Katsina state.