Rescue workers and local residents examine a damage vehicle at the site of bomb explosion in Mamund, Bajaur, on Monday. AP

The TTP said in a statement it had "successfully detonated a mine on a police" vehicle in Bajaur district, around 14 kilometres from the Afghan border.

Officials and local residents offer funeral prayers of police officers, who were killed in the roadside bombing, in Bajaur. AP

"A police truck transporting around 25 policemen for anti-polio campaign duties was targeted by an IED (improvised explosive device)," Anwar ul Haq, a senior government official in Bajaur district, told AFP. He said five officers were killed and at least 20 others wounded.

Kashif Zulfiqar, a senior police officer in the district, confirmed the death toll from the attack, which occurred in the rural area of Mamund.

In its statement, the TTP said claims the attack was associated with the polio vaccination campaign were "entirely false."