The Taliban have sent suicide bombers to mount election-day attacks on Pakistan's historic polls, a militant commander said on Thursday, following a bloody campaign which has claimed more than 100 lives.

Saturday's vote will be a democratic milestone in a country ruled for half its history by the military but the Pakistani Taliban have condemned it as un-Islamic.

They have directly threatened the Pakistan People's Party (PPP) and its main partners in the outgoing government, seriously restricting their ability to campaign, and staged a series of attacks during the campaign.

The insurgents' leader Hakimullah Mehsud had personally ordered suicide bombings on polling day, said a Taliban commander in the northwest.

"The Taliban has dispatched several of fedayeen (suicide bombers) to carry attacks on election across Pakistan," he told AFP on condition of anonymity.

AFP saw a copy of a letter apparently sent from Mehsud to Taliban spokesman Ehsanullah Ehsan, mapping out the plan for bombings.

"You take care of attacks in Punjab and Sindh. I will take care of Khyber Pakhtunkhwa and Baluchistan," it said in reference to Pakistan's four provinces.

Attacks on politicians and political parties, most of them claimed by the Taliban, have already killed 113 people since mid-April, according to an AFP tally.

Pakistan has said it will deploy more than 600,000 security personnel on polling day.

A separate pamphlet distributed by a previously unknown group in the most notorious Taliban and Al-Qaeda-stronghold of North Waziristan has warned people of punishment if they allow women to vote.

The Taliban threats have cowed the PPP, which has run a leaderless campaign. Its chairman Bilawal Bhutto Zardari -- too young to stand -- has not been seen in public.

In his absence former prime minister Nawaz Sharif and cricket legend Imran Khan have stolen the limelight. On Thursday, the last day of campaigning, they were competing to try to draw massive crowds at final rallies.

Sharif is a billionaire steel tycoon seeking a historic third term as prime minister.

The charismatic Khan is a sporting hero who has also sought to capitalise on a sympathy vote after fracturing vertebrae in a fall at a rally on Tuesday, and will address supporters from his hospital bed.

The election will mark the first time a civilian government has served a full term in the country and handed over to another through the ballot box. The outcome is considered wide open.

While Sharif is considered most likely to win, some believe the PPP can still emerge the second largest party thanks to a rural vote bank.

Despite his electrifying campaign, a question mark hangs over how well Khan will do, considering he won only one seat in 2002.

Sharif, head of the centre-right Pakistan Muslim League-N (PML-N), will spend a busy day in his political heartland in the southern city of Lahore, said his media chief Tariq Azim.

"He will meet party officials during the day before addressing a rally in the Green Town area at 7:00 pm (1400 GMT), followed by two or three other meetings in different constituencies," Azim told said.

Sharif will arrive at the 11th century Data Darbar sufi shrine at around 10:00 pm and address the final rally there. Another PML-N official said they were hoping to attract more than 100,000.

Khan will address the final rally for his centre-right Pakistan Tehreek-e-Insaf party in the capital Islamabad by live video link from his Lahore hospital bed.

Hospital staff have ordered the 60-year-old to remain immobile after he suffered fractured vertebrae and a broken rib on Tuesday when he fell from a lift raising him onto the stage at a rally in Lahore.

Taj Haider, a PPP leader in Pakistan's largest city of Karachi, said party candidates would hold meetings in their respective constituencies but refrained from discussing Bilawal's whereabouts.

The Muttahida Qaumi Movement, which was a PPP ally in the previous coalition government and controls Karachi, said it was aggresively campaigning on social media because of the threats.

Campaigning ends officially at midnight, before the Muslim holy day Friday.

The election commission has warned that violations are punishable by disqualification and six months in prison.