MILAN — An Italian prosecutor says Islamic extremists suspected in a bomb attack in a Pakistani market that killed more than 100 people had also planned an attack against the Vatican in 2010 that was never carried out.

Prosecutor Mauro Mura told a press conference in Cagliari, Sardinia, on Friday that wiretaps indicated the suspected terrorists were planning a bomb attack at the Vatican and that a suicide bomber had arrived in Rome.

Mura said the attack plans never went further and that the suicide bomber left Italy, though it wasn’t clear why. He said the wiretaps gave “signals of some preparation for a possible attack.”

Italian police said Friday they were making arrests of 18 suspected extremists, including two purported bodyguards for Osama bin Laden, who allegedly staged attacks in Pakistan and sought to topple the Pakistani government.