A crowd has beaten to death a teenage girl accused of planning to be a suicide bomber and then set her body on fire, according to police and witnesses.

A second suspect, also a teenage girl, was arrested at Muda Lawal, the biggest market in the city of Bauchi.

A spate of suicide bombings has been blamed on Boko Haram, which wants to enforce strict Islamic law across Nigeria. The group has threatened to disrupt the 28 March presidential and legislative elections, saying democracy is a corrupt western concept.

In Bauchi, the two girls aroused suspicion by refusing to be searched when they arrived at the gates of the vegetable market, said a yam seller, Muhammed Adamu. People overpowered one girl and discovered she had two bottles strapped to her body, he said. They clubbed her to death, put a tire doused in fuel over her head and set it on fire, he said.

It seems doubtful the girl was actually a bomber as she did not detonate any explosives when she was attacked, said police deputy superintendent Muhammad Haruna. He said she was the victim of mob action carried out by an “irate crowd”.

Recently some girls as young as 10 have been used to carry explosives that detonated in busy markets and bus stations, raising fears that Boko Haram may be using some of its hundreds of kidnap victims in bomb attacks. It’s unclear whether such girls detonate explosives themselves or whether the bombs are controlled remotely.

President Goodluck Jonathan last week condemned the extremists for choosing soft targets and said the series of bombings were a response to the Nigerian military’s recent success in seizing back several towns that had been in the hands of the group for months.