Pakistan has suffered a spate of bombings since Prime Minister Nawaz Sharif was sworn in last month, underscoring the challenges facing the nuclear-armed nation in taming a Taliban-linked insurgency.

A police officer in Pakistan's financial capital said Bilal Shaikh - Zardari's security chief who was always spotted next to the president during public appearances - was killed along with two others in a prosperous area of eastern Karachi.

"It seems that the suicide attacker walked up to Bilal Shaikh's vehicle and blew himself up outside the front passenger seat of the vehicle where Shaikh was seated," the senior police officer, Raja Umar Khattab, told Reuters.

About a dozen other people were wounded.

A police escort was accompanying Shaikh's white armored  sports utility vehicle when the attack took place. Police said an unidentified attacker walked up to the car and blew himself up just as Shaikh opened the door to get out.
No one immediately claimed responsibility for the attack, which took place on the eve of the start of the holy Muslim month of Ramadan that is observed in Pakistan from Thursday.

The latest wave of attacks across Pakistan has brought an end to a period of relative calm after Pakistan's first ever transition between elected civilian governments that brought Sharif to office for the third time in a May election.

Shaikh - who had survived an earlier assassination attempt near his home in Karachi about a year ago - used to change his routes several times while travelling around one of Pakistan's most violent cities.

Like Zardari, he belonged to the Pakistan People's Party, which had been in power before the May election. Taliban-linked militants had previously targeted the secular party.

Both Zardari and Sharif have issued separate statements condemning the attack, a private television channel reported.

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