At least five people have been killed and 10 wounded after a suicide bomber blew himself up outside a leprosy hospital on the outskirts of the northeast Nigerian city of Maiduguri.

At least five people have been killed and 10 wounded after a suicide bomber blew himself up outside a leprosy hospital on the outskirts of the northeast Nigerian city of Maiduguri, emergency services said Sunday.

The bomber, who tried to gain access to the hospital, detonated his explosives outside the building at around 5:30 pm local time (16:30 GMT) on Saturday.

Local resident Ibrahim Bulama said the bomber was one of three men who were dropped off near the hospital by a SUV vehicle.

"They looked around for a while, obviously trying to sneak into the hospital," Bulama said, adding that the facility was being guarded by civilian vigilantes who are assisting the military in the fight against Boko Haram terrorist group.

"Suddenly, the explosives on one of them went off. The other two fled in the confusion. Five people were killed and 10 others injured."

There was no immediate claim of responsibility for the bombing, but Nigeria's Borno state, where the attack took place, has been the hardest hit by the Boko Haram armed insurgency which has left at least 15,000 people dead.

Danlami Ajaokuta, a civilian vigilante fighting Boko Haram, confirmed the hospital explosion and added that there had been a failed suicide attack by two women in Jakarna village, about 40 kilometres (25 miles) from Maiduguri on Saturday afternoon.

"Two female suicide bombers died when the explosives on one of them went off prematurely while they were waiting for a bus along the highway in Jakarna," Ajaokuta said.

"Residents from the village heard a huge explosion and when they arrived at the scene they found one of the bombers in parts while the other lay dead face down.

"Her explosives were still intact."

Ajaokuta added that bus drivers have been refusing to pick up female passengers on the road outside Maiduguri since March, when three female suicide bombers blew themselves up at a bus stop in the area.

The armies of Nigeria, Chad, Niger and Cameroon have been fighting a joint campaign against Boko Haram for several months, pushing militants out of captured towns and villages.