Sharif has vowed to fly home from London on Monday to counter President Gen. Pervez Musharraf's re-election bid and run for Parliament, despite veiled threats from senior officials to put him back in jail.
Sharif was toppled in Musharraf's 1999 coup, convicted on charges of hijacking and terrorism and sentenced to life imprisonment before being released into exile in Saudi Arabia.
Information Minister Mohammed Ali Durrani said Sharif was allowed to leave Pakistan after he made pledges to leaders from countries such as Saudi Arabia and Lebanon not to return for 10 years.
Durrani said Sharif "should honor his word," and "should respect the commitment he had made with certain Islamic countries" to secure his release.
"He should not come (back)," Durrani told The Associated Press.
In a sign the government is planning a bumpy landing for Sharif, officials said Friday that police had detained hundreds of supporters from his Pakistan Muslim League-N party in his political stronghold.
Sharif's party denounced the latest moves as politically motivated, and said they would backfire on Musharraf.
Meanwhile, an anti-terrorism court in the eastern city of Lahore on Friday ordered the arrest of Sharif's younger brother Shahbaz in a murder case, said Aftab Ahmed Bajwa, a lawyer for the plaintiff.
He is charged with ordering police to kill five men who were gunned down in Lahore in 1998. At the time of the killings, Shahbaz was the chief minister, or top executive, of Punjab province, and Nawaz was Pakistan's prime minister.
On Wednesday, the father of one of the victims asked the court to arrest Shahbaz after hearing that he was due to return to Pakistan, Bajwa said. Shahbaz has denied the allegation.
Meanwhile, an anti-corruption court in Rawalpindi held a hearing in a case involving allegations that the Sharif family defaulted on a bank loan and owned property beyond their known financial means, said Zulfiqar Ahmed Bhutta, a prosecutor for the state National Accountability Bureau.
The cases date back to 2001 and 2002. Hearings were adjourned for years, but reopened late last month following an application by the government.
The judge adjourned the case until Sept. 13 to ensure the next hearing takes place after the Sharifs are in the country, Bhutta said.
Ahsan Iqbal, spokesman for Sharif's Pakistan Muslim League-N party, said the moves against the Sharifs "show complete panic in the ranks of the government."
Musharraf, a key ally in the U.S. war on terror whose popularity has declined since his failed attempt to fire the country's top judge earlier this year, has repeatedly said the Sharifs must remain in exile for 10 years under the terms of a deal reached in 2000. But the Supreme Court ruled last month they were free to enter Pakistan and that their return should not be obstructed.
Thousands of Sharif supporters are planning to converge on Islamabad to welcome him, but there are expectations that authorities will try to block them. The Sharifs plan to travel to Lahore, the capital of Punjab and their power base, by road.
Iqbal said more than 1,300 party supporters were arrested in raids on their homes across Punjab, which includes Islamabad airport, in the past three days.
"If the government uses illegal tactics and blocks them, that will increase political tension in the country and bring people onto the streets," he said.
A police official in Lahore acknowledged that officers had picked up Sharif supporters, but put the number at about 350. He spoke on condition of anonymity because he was not authorized to make media comments.
Musharraf is expected to seek re-election by lawmakers by mid-October, but has yet to make a public commitment to resign as army chief if he continues as president. Many experts say that to keep his uniform—the main source of his power—beyond 2007 would violate the constitution.
To help smooth the way, Musharraf is trying to strike a deal with another exiled former prime minister, Benazir Bhutto, that could lead them to share power.
Bhutto has been pressing the pace of talks so that she can decide when to return.
However, Durrani, the information minister, said Friday a final decision would come in the Muslim holy month of Ramadan, which begins in mid-September.
"The political process is moving forward. The government will not allow that political process to be disturbed," Durrani said.
Last Mod: 08 Eylül 2007, 09:39