( AFP ) - Pakistan locked former premier Benazir Bhutto under house arrest, blocking her from a planned rally to protest President Pervez Musharraf's imposition of a state of emergency.
Nearly 200 police sealed off Bhutto's house in Islamabad with barbed wire and a magistrate went inside, apparently with the arrest order, hours before she was due to lead the demonstration in neighbouring Rawalpindi.
The stand-off raised the stakes in the political crisis which has engulfed the country and presented military ruler Musharraf with the most serious challenge to his rule since he seized power in a coup eight years ago.
"She is being placed under house arrest," a senior government official told AFP on condition of anonymity.
A senior leader of Bhutto's Pakistan People's Party, senator Anwar Baig, told AFP outside her house: "This is illegal confinement. This is illegal detention of a democratic leader."
Despite weeks of speculation about a power-sharing arrangement between them, Bhutto on Wednesday called for mass demonstrations against Musharraf's decision last Saturday to declare a nationwide state of emergency.
Political gatherings were banned, the constitution was ssuspended, the chief justice -- a longtime Musharraf nemesis -- was sacked, and more than 3,000 people arrested.
"We tried to convince Benazir Bhutto to cancel the rally but she did not agree, and we had no choice but to implement these restrictions," a senior police official told AFP.
The government also deployed 6,000 police officers to stop the protest in Rawalpindi, completely cordoning off the planned venue in the garrison city with barbed wire and concrete blocks.
"Under no circumstances will the rally be allowed. The law will take its course against anyone who defies it," Rawalpindi police chief Saud Aziz told AFP.
Police also warned that up to eight suicide bombers have infiltrated Rawalpindi, raising the spectre of a repeat of the double suicide blast that killed 139 people at her homecoming parade in Karachi on October 18.
"There is a very credible threat of suicide attacks. That is why the government imposed the restrictions," interior ministry spokesman Javed Cheema told AFP.
Bhutto's Pakistan People's Party, however, said it had booked the venue in the city centre location of Liaqat Bagh and vowed to press on with the rally in any case.
Bhutto told the BBC in an interview broadcast overnight that Musharraf's pledge to hold elections by mid-February and quit his other role as army chief were not enough to stem the crisis gripping the country.
"It is too vague, it is too general, it is an attempt to break the momentum of the opposition," she said, calling for Musharraf to take off his uniform by November 15 at the latest.
Bhutto's party had so far stayed off the streets, leaving lawyers to bear the brunt of police violence against protesters and leading to suspicions that she is in secret talks on a power-sharing deal with Musharraf.
But she turned on Musharraf this week, vowing to press on with Friday's Rawalpindi protest and to hold a "long march" from Lahore to Islamabad on November 13 if he does not meet her demands.
"Two of the main issues demanded by Benazir Bhutto have been addressed and there is no point for her to hold this rally. It's complete political point-scoring on her part," deputy information minister Tariq Azeem told AFP.
Musharraf's election announcement Thursday was welcomed by the United States and Britain but both urged further steps, including the restoration of the constitution.
Senior US senators meanwhile sought to put pressure on Musharraf, introducing a resolution urging a review of military assistance to Pakistan while the state of emergency remains in effect.
It came as Washington voiced increasing alarm that Pakistan's nuclear arsenal could fall into the hands of Islamic militants as the political crisis drags on.