ISLAMABAD (AFP) - Pakistani lawmakers on Tuesday began voting for a new president, marking an end to the five-year term of outgoing Asif Ali Zardari whose party lost May's general elections.

An official from the Pakistan election commission told AFP that lawmakers in the Senate, National Assembly and the four provincial assemblies have started casting their votes to elect a new head of state.

Mr Mamnoon Hussain, a businessman from the southern city of Karachi and close ally of Prime Minister Nawaz Sharif, is the most likely to replace Mr Zardari.

A long-serving member of the ruling Pakistan Muslim League-N (PML-N), Mr Hussain addressed a party meeting in Islamabad on Monday.

"Describing the office of president as the symbol of federation, the presidential candidate pledged to serve the country and its people in his capacity as president," a statement issued by Mr Sharif's office said.

Mr Zardari's opposition Pakistan People's Party (PPP) has boycotted the election, complaining it was not consulted on bringing the date forward from Aug 6, and its absence means Mr Sharif's candidate is certain to win.

Mr Hussain's loyalty to Mr Sharif and low-profile will shore up the prime minister's authority and provide a stark contrast to Mr Zardari, considered a sharp political operator behind the scenes.

Mr Hussain first impressed Mr Sharif in 1999 as president of the Karachi Chamber of Commerce and Industry (KCCI) and was made the governor of southern Sindh province.

"He had no political affiliation until 1999 but his polite discourse and professional ability impressed Nawaz Sharif who made him governor of Sindh," Mr Azhar Haroon, the current president of KCCI, said.

In a reminder of the enormous challenges Pakistan faces, Taleban militants launched a brazen attack on a prison in the north-west of the country overnight, escaping with more than 200 prisoners after a three-hour gunfight with security forces.

A debilitating power crisis also needs to be solved and US relations are complicated by drone attacks targeting militants.

Supporters say Mr Hussain's election could be important domestically by giving the south some stake in the federal administration, otherwise dominated by Punjab, Sharif's power base.

The other candidate is retired Supreme Court judge Wajihuddin Ahmed, nominated by the third largest party of cricket hero Imran Khan.

Result of the polls is expected to be announced late on Tuesday.

Constitutional amendments passed by the last PPP government mean that the presidency is again a ceremonial post, a status likely to be cemented by the fact that Mr Hussain has little personal clout.

Mr Sharif won a commanding general election victory in May, which marked the first time a Pakistani civilian government completed a full term in office and handed over to another at the ballot box.

Political analyst Hasan Askari says Tuesday's election will return Pakistan to a strong executive prime minister and a ceremonial head of state.

"Mamnoon Hussain is a political lightweight and this is the reason Mr Sharif chose him to become the next president," he told AFP.

But the last PPP government had a turbulent relationship with Pakistan's top court and Mr Askari warned that its boycott could lead to rocky relations with the PML-N.

"Mamnoon Hussain will be elected easily and it will be an easy walkover, but he will start his term with a strong controversy.

"In the long-term it will cause tensions between PPP and PML-N," he said.