Former Pakistani Prime Ministers Nawaz Sharif and Benazir Bhutto have called for the formation of a caretaker government to oversee elections next year.

At a meeting in London, the two former leaders expressed doubt that free and fair elections could be held under President Pervez Musharraf.

Sharif and Bhutto also pledged to return to Pakistan before the parliamentary elections. General Musharraf has vowed to block their return.

Since May, Sharif and Bhutto have been working to unite their opposition groups against the Pakistani leader

General Musharraf overthrew Sharif in a military coup in 1999.

Bhutto, who was Pakistan's prime minister twice in the 1980s and 1990s, fled the country in 1999 to avoid arrest on corruption charges.