The former Pakistani PM, Benazir Bhutto, has said Pervez Musharraf must quit as head of Pakistan's military if he wants to continue as president.
She spoke after the two were reported to have met in what was said to be a bid to strike a power-sharing deal.
Pakistani reports said Gen Musharraf and Ms Bhutto had met in Abu Dhabi in the United Arab Emirates.
Gen Musharraf is facing increasing political opposition and rising violence from Islamist militants.
More than 180 people have been killed in attacks since the Red Mosque in the capital, Islamabad, was cleared of militants in a bloody siege three weeks ago.
More than 100 people were killed as soldiers stormed the mosque.
Talks with government
"I have very grave reservations about a uniformed president, and I believe it blurs the distinction between the civilian and military rule," Ms Bhutto told Britain's Sky television on Sunday.
Ms Bhutto has made no secret that her Pakistan People's Party has been holding talks with the government, but neither she nor Gen Musharraf has commented on Friday's reported meeting in Abu Dhabi.
"We have already said that our negotiations are going on and we have achieved forward movement on some matters," she told Pakistan's Geo Television.
"But there are some matters on which there are two opinions and we have to look further into these issues."
Ms Bhutto has lived in exile since leaving Pakistan in 1999 after serving as prime minister for two terms in the 1980s and 1990s.
She says corruption charges against her and her husband are politically motivated.
She has been trying to engineer a comeback, but the constitution would have to be changed to allow her a third term as prime minister.
Gen Musharraf, who took power in a bloodless coup in 1999, is expected to seek re-election later this year.
Speculation is running high that he may strike a deal with Ms Bhutto for her support in exchange for allowing her return to Pakistan to run for prime minister.
But Gen Musharraf has repeatedly rejected assertions by Ms Bhutto and another former prime minister, Nawaz Sharif that they will return for the general elections due later this year.