MIRANSHAH, Pakistan (AFP) - Militants blew up the election office of an independent candidate in northwest Pakistan on Saturday, adding to security fears ahead of historic national polls next month.

No one was hurt in the bombing in Miranshah, which is the main town in North Waziristan and a known hub of Taleban and Al-Qaeda-linked militants, bordering Afghanistan.

But the bombing is likely to fuel concerns that violence will mar the national and regional elections on May 11, which will mark the country's first democratic transition of power after a civilian government has served a full term in office.

"Militants blew up the election office of Kamran Khan with explosive at around 5am (8am Singapore time)," an intelligence official in Miranshah told AFP, adding that all three rooms of the office were destroyed.

Residents in Miranshah confirmed the bombing and told AFP that an adjacent mosque was also damaged in the blast.

Mr Khan is a former legislator from North Waziristan who supported the outgoing government led by the Pakistan People's Party, the official said.

Nobody immediately claimed responsibility for the attack.

But umbrella Taleban faction Tehreek-e-Taleban Pakistan has made death threats against the three main secular parties that made up the outgoing government and who backed army operations against the Islamist militants.

On Thursday, militants shot dead a candidate for outgoing coalition partner the Muttahida Qaumi Movement (MQM), the first to die in the election campaign, in an attack claimed by the Taleban.

Pakistan says more than 35,000 people have been killed as a result of terrorism in the country since the 9/11 attacks on the United States.