KANO, Nigeria (AFP) - A suicide attack targeting a senior police official's convoy in eastern Nigeria on Monday killed 11 people and wounded 20, a rescue source said, with the senior officer unharmed.

Police said the attack in the Taraba state capital Jalingo saw a motorcycle ram into the police convoy amid a wave of similar violence attributed to Islamist group Boko Haram.

Authorities provided an official death toll of three people, including two passers-by and the bomber, with a police motorcyclist wounded.

However, the rescue official put the death toll at 11, including a policeman, with 20 wounded.

"Eleven people died," the rescue official said on condition of anonymity because he was not authorised to talk to the press. "One policeman was among them. There are 20 injured."

In describing the attack, police spokesman Ibiang Mbaseki said "a bomber on a motorcycle rammed into the police rider (motorcycle escort). The bomb went off. The windshield of the (state) police commissioner's car was shattered."

There was no immediate claim of responsibility and police declined to name any suspects, though the attack was similar to others carried out by Islamist group Boko Haram.

"For now, we are not mentioning anybody as suspects," said Mbaseki. "An investigation will be carried out to determine who was responsible."

Taraba state has not been known to be targeted by Boko Haram, though the state borders others that have been repeatedly hit by such violence.

The alleged mastermind of a Christmas day attack on a church near the capital Abuja which killed at least 44 people was re-arrested in Taraba state in February after having earlier escaped from custody.

President Goodluck Jonathan condemned Monday's attack in a statement, urging "Nigerians and foreigners living in the country not to be discouraged or deterred from going about their regular affairs by the persistence of the mindless bombings and gun attacks."

Speaking at the opening of a summit of the six-nation Lake Chad Basin Commission in Libreville, President Idriss Deby Itno of neighbouring Chad called for the creation a joint regional force to battle the spread of Boko Haram.

"I am demanding the creation of a joint deterrence force. We have to make this decision here today," he said. "Our basin is exposed to insecurity because of the permanent threat posed by Boko Haram."

Officials and experts have expressed concern that Boko Haram may be building ties with Al-Qaeda and expanding beyond Nigeria's borders to threaten the region, but diplomats say the group's agenda is domestically focused.

Nigeria has been hit by near daily gun-and-bomb attacks, mainly in the country's north, that have shaken Africa's most populous nation and largest oil producer.

On Sunday, attacks on churchgoers in the northern cities of Kano and Maiduguri left a total of 23 people dead, security sources and an NGO have said.

Also Sunday, unknown gunmen shot dead three policemen on patrol in an ambush in northern Katsina state, a police spokesman said Monday.

Nigeria is roughly divided between a mainly Muslim north and a predominantly Christian south. Taraba is located along the eastern-central border.

Boko Haram's increasingly bloody insurgency has claimed more than 1,000 lives since mid-2009. Police and soldiers have often been the victims, but Christian worshippers have also been targeted.

The group also claimed responsibility for a suicide attack at UN headquarters in Abuja which killed at least 25 people last August.

Boko Haram initially claimed to be fighting for the creation of an Islamic state in Nigeria's north, but its demands and structure have become less clear in recent months.

It is believed to have a number of factions, some with political motives, as well as a hardcore Islamist wing. Criminal groups are also believed to have carried out violence under the guise of Boko Haram.