Mushahid Hussain Sayed, the secretary general of PML-Q, also alleged that Zardari had not accounted for USD 60 million in bank accounts that were recently unfrozen by Swiss authorities, who dropped a money laundering case against him.

"I feel it would be in the interests of Pakistan, democracy and the Pakistan People's Party that this office (of President) remains above controversy and I would humbly request Mr Zardari that he should withdraw his candidature in the supreme national interest and in interest of democratic stability," Sayed told reporters outside Parliament.

The presidential election on September six is widely expected to be a triangular contest between Zardari, Sayed and former Supreme Court Chief Justice Saeed-uz-Zaman Siddiqui, who was fielded by the PML-N after it broke away from the PPP-led ruling coalition. Saturday is the last day for withdrawing nominations for the presidential polls.

Referring to a Financial Times report that had raised questions about the state of Zardari's mental health, Sayed said, "I do not want to comment on a person's mental health. But since he (Zardari) is a public figure contesting a public office the office of supreme commander of the armed forces, who has his hand on the nuclear trigger, who is also chairman of the Nuclear Command Authority it is legitimate for the people of Pakistan to ask whether that story is true or not and what is his response," he added.

It is a requirement that any person contesting the presidential polls must be "physically and mentally fit", Sayed pointed out.

PPP spokesperson Farahnaz Ispahani had on Tuesday said that Zardari "is fit and well" as had been shown by "his masterful handling of Pakistani politics since the assassination of (his wife and party chairperson) Benazir Bhutto" in December last year.

"Distorting the private health records of our nation's leader is a remnant of a darker era of our national history," Ispahani had said.

Referring to the decision by Swiss authorities to release USD 60 million that had been frozen in bank accounts over the past decade, Sayed said: "The people of Pakistan would like to know what is the source of this wealth because this wealth has not been declared in Mr Zardari's tax returns."

Sayed renewed his challenge that Zardari should face him in a live television debate "so that people can find answers to their questions".

The PML-Q leader also took a dig at Zardari's all powerful status in the government, saying he should not contest the presidential polls as he already had many "major responsibilities".