Zardari, who had been widely expected to win, had secured 458 out of 702 electoral college votes, according to partial Election Commission results.

"It's not only a victory for Mr Zardari and the Pakistan People's Party but it's a victory for Benazir Bhutto's dream of a democratic political system," said Bhutto party spokeswoman Farzana Raja as party workers chanted "long live Bhutto".

Bhutto was killed in a suicide attack on Dec. 27.

Members of the two-chamber Parliament and four provincial assemblies voted for a replacement for Pervez Musharraf, who resigned last month.

Investors hope the election will bring some stability after months of political turmoil that has helped drag stocks and the rupee sharply lower.

Zardari, known as a polo-playing playboy in his younger days, will have to contend with a host of problems that have raised fears for the prospects of the nuclear-armed US ally, including militant violence and an economy in tatters.

Underscoring the danger, a suicide car-bomber attacked a police post in the city of Peshawar, killing at least 30 people, five of them policemen, and wounding 70.

The blast destroyed the post and brought down roofs of nearby buildings. Some people were still under the rubble, said provincial police chief Malik Naveed Khan.

The bomber's target was probably the provincial assembly, where members were voting in the election, he said.

Zardari, 53, is close to the United States and has repeatedly stressed Pakistan's commitment to the campaign against militancy.