By Syed Raza Hassan
ISLAMABAD, April 25 (Reuters) - At least four people were killed in the Pakistani city of Karachi on Friday when a roadside bomb aimed at a bus carrying Shi'ite Muslim worshippers exploded, police said.
"We suspect that a bus coming from a Shi'ite mosque was the likely target," provincial police chief Iqbal Mehmood said in remarks broadcast by Pakistani television channels.
Deputy Inspector General Khalique Shaikh said the bomb went off just after the bus drove past and that all those who were killed were civilians who happened to be nearby.
"It seems that the bombing missed the target as the IED (improvised explosive device) went off minutes after the bus had passed through the scene," he told Reuters.
"People in the bus suffered minor injuries and the windscreen and windows were shattered due to the impact."
Pakistan has been grappling with a tide of sectarian violence, with Sunni Muslim Taliban militants frequently attacking Shi'ites they see as infidels who deserve to die.
No one claimed responsibility for the attack, which took place after talks between the government and Taliban to end years of fighting which has killed tens of thousands of people.
The tentative discussions have yielded no result and the militants ended a 40-day ceasefire last week.
On Thursday a police officer known for his tough stance against the Taliban was killed in a suicide bombing in Karachi.
"The attacks have spiked after the end of the ceasefire. The entire country is under threat," the regional information minister, Sharjeel Memon, said in televised remarks.
"The federal government should now reconsider their reconciliation policy," he said.
"The only difference is that before militants used to claim responsibility for attacks, but now they just remain silent." (Editing by Maria Golovnina and Andrew Roche)