Pakistani election officials have rejected former prime minister Benazir Bhutto's third and final nomination to stand in elections next month.

With the leaders of two major political parties out of the elections, there remains no credibility to the electoral process

Raza Rabbani, PPP secretary general

Ms Bhutto was turned down for one of a number of seats reserved for women in Sindh, her home province, because of a conviction for failing to answer corruption charges.

Two other nominations from Ms Bhutto had already been rejected in Sindh.

Although she is appealing, the ruling in effect means she is out of the election, a BBC correspondent in Pakistan says.

Bhutto's party is a main contender in the vote

Ms Bhutto's supporters staged angry protest demonstrations against the ruling.

The Pakistan People's party which she leads said there was no credibility to the election.

"The farce is complete," its secretary-general told Reuters news agency.

Under election rules a convict stands disqualified

Abdul Ghani Soomro, Lakarna returning officer

Another former prime minister, Nawaz Sharif, withdrew from the polls on Saturday in protest at Ms Bhutto's treatment.

Opposition politicians say the two former leaders have since been in contact to work out a joint strategy.

Both Mr Sharif and Ms Bhutto, who are living in exile, had filed nomination papers in defiance of sweeping new laws brought in by the military authorities, which bar them from running on 10 October.

Protest

The announcement that Ms Bhutto's attempts to run had failed came in the southern port city of Karachi.

This decision is aimed at lodging my strong protest against the unethical, illegal and unconstitutional measures

Nawaz Sharif

"She is convicted, that is why I am rejecting her papers," Ahmed Ali Halopota, the city's returning officer, said.

Earlier on Sunday, Ms Bhutto's candidacy in her family's stronghold town of Larkana was rejected.

And on Friday she was barred from standing in a rural constituency in Sindh on the same grounds.

About 500 Bhutto supporters, who were in Larkana for the ruling, protested against the decision.

Solidarity

Election officials surprised many last week when they accepted Mr Sharif's nomination papers.

Musharraf says he is keen to restore democracy

But on Saturday his Pakistan Muslim League party made clear he would not run.

Party officials said Mr Sharif wanted to express solidarity with Ms Bhutto, and to show opposition unity.

Military ruler General Pervez 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 recently made sweeping changes to the constitution.

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