A statement issued by Mr Shari's Pakistan Muslim League party said the decision was aimed at registering his protest against the military regime's "unethical and unconstitutional measures".

This decision is aimed at lodging my strong protest against the unethical, illegal and unconstitutional measures of (Pakistan's) military regime under the garb of restoring true democracy.

Nawaz Sharif

In a surprise decision, election officials in Pakistan had accepted Mr Sharif's nomination papers earlier this week, allowing him to run in the general elections.

But on Thursday, they rejected the application of another former prime minister, Benazir Bhutto.

Both Mr Sharif and Ms Bhutto, who are living in exile, had filed nomination papers in defiance of the law barring them.

Solidarity

"I have decided to withdraw my nomination papers filed and duly accepted for the forthcoming elections," Mr Sharif said in the statement, read by PML chairman Raja Zafaral Haq. "This decision is aimed at lodging my strong protest against the unethical, illegal and unconstitutional measures of (Pakistan's) military regime under the garb of restoring 'true democracy."

Mr Sharif's party officials said the decision was taken to express solidarity with Ms Bhutto, and to show opposition unity.

Musharraf says he is keen to restore democracy

Ms Bhutto had expressed disappointment at being disqualified and said her rejection was aimed at dividing the opposition.

"I am happy for Nawaz Sharif that he has been allowed to run... But I think they are trying to divide the opposition. But let me tell you the opposition will remain united against the military government, she told the BBC.

Meanwhile, hundreds of Ms Bhutto's supporters held several rallies across Sindh on Saturday to protest against her rejection.

The police said they detained more than 100 activists of Ms Bhutto's Pakistan People's Party to maintain law and order.

General Musharraf, who overthrew Mr Sharif in a bloodless coup in October 1999, says he has called elections to restore democracy in Pakistan.

But many people have raised doubts about his intentions - particularly after he made sweeping changes to the constitution.

Critics say the new powers are intended to maintain General Musharraf's grip on authority - despite the elections.