At least twelve people were killed and 11 injured when three roadside bombs targeting a polio vaccination team in Pakistan’s restive northwest exploded on Saturday, officials said.

At least twelve people were killed and 11 injured when three roadside bombs targeting a polio vaccination team in Pakistan's restive northwest exploded on Saturday, officials said.

The blasts near the Afghan border were the latest attack on efforts to stamp out the crippling disease in Pakistan, which is one of only three countries where polio remains endemic.

Eleven paramilitary troops and one child died when the bombs detonated in the Lashora area of Jamroud Tehsil in Khyber Agency, 30 kilometres (miles) southwest of Peshawar, senior official Jahangir Khan told AFP.

The troops were protecting a convoy of anti-polio campaigners, Khan said, adding that two vehicles belonging to the medical team were damaged in the explosions.

Polio persists in Pakistan with militant groups seeing vaccination campaigns as a cover for espionage. There are also long-running rumours about polio drops causing infertility.

According to the World Health Organization (WHO), Pakistan recorded 91 cases of polio last year, up from 58 in 2012.

WHO has warned that Peshawar is the world's "largest reservoir" of polio.

Pakistan's struggle to defeat polio stands in stark contrast to its neighbor and great rival India, which recently celebrated three years since its last polio case.

Afghanistan and Nigeria are the other countries where the disease remains.