Police blocked opposition leader Benazir Bhutto from visiting Pakistan's deposed chief justice on Saturday, as President Pervez Musharraf resisted US calls to end emergency rule.
Bhutto, who herself was kept under house arrest for most of Friday, tried to approach former chief justice Iftikhar Chaudhry's home, where he is being detained, but police parked two trucks on the road to block her path.
After imposing emergency rule and suspending the constitution a week ago citing a hostile judiciary and rising militancy, General Musharraf sacked most of the Supreme Court's judges and has since replaced them with more amenable ones.
"He is the chief justice, he is the real chief justice," Bhutto blared over a megaphone, demanding they all be reinstated.
Bhutto will defy Musharraf and go ahead with a pro-democracy motorcade from Lahore to Islamabad next week, after police scotched a protest by her Pakistan People's Party in the garrison town of Rawalpindi adjoining Islamabad on Friday.
On Friday, police used batons and teargas to break up small protests in several parts of the country, but demonstrations have been relatively small by Pakistani standards.
Pakistan's slide into political uncertainty has accelerated over the past week with military chief Musharraf's imposition of emergency rule scaring foreign investors and spooking domestic markets. Thousands of Musharraf opponents have been arrested.
Bhutto, the Pakistani politician most able to mobilise masses, was due to meet foreign diplomats later in the day.
She briefly joined journalists protesting outside the offices of a television channel against a blackout on private news broadcasts. BBC and CNN are also off the air, though newspapers are still publishing freely.
Bhutto is due to head to Lahore on Sunday, and has said Musharraf can defuse the protest if he restores the constitution, removes his army uniform and calls elections by mid-January.
Musharraf has said elections will be held by February 15, about a month later than they were due. He also said he would quit as army chief and be sworn in as a civilian president once new judges appointed to the Supreme Court struck down challenges against his re-election.
Officials say Musharraf will likely keep the emergency short.
"The emergency will end within a month or two. It all depends on the law and order situation," said Attorney General Malik Abdul Qayyum.
Bhutto has been holding power-sharing talks with Musharraf for months and political analysts say cooperation between the pair -- which the United States was earlier said to have been encouraging -- is still possible.
The United States kept up pressure on Musharraf, who took power in a bloodless 1999 coup and is regarded as a close ally in the fight against al Qaeda and the Taliban, calling for an end to emergency rule he imposed a week ago citing a hostile judiciary and rising militancy.
"Free and fair elections require a lifting of the state of emergency," said Gordon Johndroe, spokesman for the White House National Security Council.
The United States also called for the release of political party members and peaceful protesters, he said.
An Interior Ministry spokesman said 2,500 people had been detained since the emergency was declared, though Bhutto's Pakistan People's Party say 5,000 of their activists have been picked up over the past few days.
President George W. Bush has said Musharraf can't be army chief and president at the same time.
But many ordinary Pakistanis doubt Musharraf will follow through on his pledge, saying quitting as army chief would erode his authority in the nuclear-armed state.
US Defence Secretary Robert Gates said on Friday he was concerned instability could distract Pakistani forces who have been fighting Islamists in tribal areas bordering Afghanistan -- an area in which Osama bin Laden is believed to be hiding.
(Additional reporting by Augustine Anthony and Rehmatullah Mehsud)