Men armed with knives slit the throats of three Chinese doctors in a pre-dawn attack Sunday in Nigeria's volatile northeastern town of Potiskum, police said, in the latest such killings in recent months.

Residents added that the Chinese, whose bodies were found by neighbours, were employees of the state ministry of health and had been living in the city for one year.

"Unknown attackers scaled over the fence of an apartment in Potiskum housing three Chinese doctors around 1:00 am and slit their throats," Yobe State police commissioner Sanusi Rufa'i told AFP.

"No arrest has been made," Rufa'i added.

Rufa'i did not say if the Islamist group Boko Haram which has been active in Potiskum, some 100 kilometres (60 miles) from state capital Damaturu was responsible for the attack.

"It is still premature to point any accusing fingers but we have commenced investigation to unravel the killings," he said.

A local resident said the bodies of the Chinese were found in their room Sunday morning by neighbours who alerted the security agents who in turn forced the door open.

The three Chinese doctors were found slain after "people became worried when the doctors did not open their door in the morning," a resident who did not want to be named told AFP.

He said the victims had their throats slit, but it was not immediately clear if the assailants also came with guns.

The killings followed Friday's slaying of health workers in Kano.

Gunmen on three-wheeled motorbikes killed 10 polio vaccinators in two separate attacks in Kano on Friday, but it was unclear whether the two incidents were linked.

Nigerian President condemned Friday's killings, describing it as "dastardly terrorist attacks" and vowed to track down the perpetrators.

Sunday's attack also followed a spate of killings of Chinese nationals in the country's restive northeast in recent months.

In November last year, gunmen shot dead two Chinese construction workers in nearby Borno State, the stronghold of the Boko Haram extremists.

On October 19, a Chinese construction worker was killed in the state capital Maiduguri while another Chinese national was shot dead on October 7 in the town of Gubio, outside Maiduguri.

The killings of the Chinese nationals at the time prompted Beijing to lodge a diplomatic protest to Nigerian authorities.

Although no group claimed responsibility for the attacks, they were similar to previous ones against foreigners carried out by Boko Haram extremists.

Boko Haram has claimed to be fighting for the creation of an Islamic state, but its demands have shifted repeatedly and it is believed to include various factions. Criminal gangs and imitators are also suspected of carrying out violence under the guise of the group.

Violence linked to Boko Haram is believed to have left some 3,000 people dead since 2009, including killings by the security forces.

Nigeria, Africa's most populous nation and largest oil producer, is divided between a mainly Muslim north and predominantly Christian south.