Former Pakistan cricket star Imran Khan's party has enjoyed a late surge of support ahead of elections in Pakistan.

The failure of the major parties to capture a commanding lead raises the risk a weak government will emerge.

This will cloud optimism over the first transition between civilian governments in a country that has been ruled by the military for more than half its history.

The party of former prime minister Nawaz Sharif looks set to win the most seats.

This would return Mr Sharif to power 14 years after he was ousted in a military coup, imprisoned and later exiled.

But Mr Khan could end up holding the balance of power if there is no clear-cut winner.

In a sign of his popularity, 35,000 supporters turned up yesterday at a rally in Islamabad that he did not even attend.

The 60-year-old is in hospital after suffering injuries in a fall from a mechanical lift at a rally this week, which may also win him sympathy votes.

Five people were injured after a bomb exploded outside an election campaign office in Pakistan, local media reported.

The device went off in front a building being used by the Pakistan People's Party (PPP).

Campaigning for the elections has ended, with candidates holding final rallies.

The election will mark the country's first successful transition from one civilian government to another in its 66-year history.

However, the run-up to the election has been marred by violence in which more than 100 people have been killed.

Yesterday, gunmen kidnapped the son of a former Pakistani prime minister.

A letter from the leader of the Pakistani Taliban has also revealed plans for suicide bomb attacks on election day.

Pakistani Taliban leader Hakimullah Mehsud, in a message to the group's spokesman, outlined plans for the attacks, including suicide blasts, in all four of the country's provinces on polling day.

"We don't accept the system of infidels which is called democracy," Mr Mehsud said in the letter, dated 1 May.

Since April, the al-Qaeda-linked Pakistani Taliban has killed more than 100 people in attacks on election candidates and rallies.

They have targetted particularly those of secular-leaning parties, in an attempt to undermine elections they regard as un-Islamic.

The attacks have prevented candidates from the three main parties in the ruling coalition from holding big rallies.

Instead, they have relied on door-to-door campaigning or small meetings in homes or on street corners.