Two exiled former Pakistan prime ministers, Benazir Bhutto [Images] and Nawaz Sharif, have asked Pakistan President General Pervez Musharraf [Images] and Prime Minister Shaukat Aziz to resign by July 31.

Bhutto and Sharif warned that the 16-party opposition alliance will begin a process of impeachment against the two if they do not step down.

At their six-hour-long meeting in London [Images], the leaders of Alliance for Restoration of Democracy endorsed the Charter of Democracy agreed between Sharif and Bhutto recently to end the military hold over politics.

It also adopted a host of resolutions condemning the use of state force in Balochistan, Waziristan and victimisation of political opponents by the military junta.

Addressing the meeting, both Sharif and Bhutto accused Musharraf of undermining national sovereignty and endangering the unity of the country.

Sharif said Musharraf has done 'worse damage to Pakistan than what India inflicted on it'.

Bhutto told reporters that a committee was being constituted which would decide whether both options -- impeachment of the president and no-confidence motion against the prime minister -- would be exercised.

Asked if Musharraf would try to go ahead with his plan to get re-elected by the present assemblies, Sharif said in that case all ARD legislators would quit.

Bhutto said, "If Musharraf refuses to have free, fair and impartial elections open to all political parties and political personalities then that means elections will not be a solution for restoration of democracy."

"We hope that he will change his attitude.... and allows transition from a military dictatorship to democracy. If he closes the door on elections, then, obviously, people will look at alternatives," she said.

Asked if ARD would take part in elections under the supervision of Musharraf, Sharif said, "We will not walk into the trap laid by the general to get legitimacy for himself."

Both the leaders said they would be returning to Pakistan before the elections.

The meeting demanded that all 'politically motivated' cases against Bhutto and other leaders be withdrawn immediately and those living in exile be allowed to safely return to Pakistan.