( AP ) - Former Prime Minister Nawaz Sharif landed in Pakistan Monday, returning from exile to lead a campaign to topple the country's U.S.-allied military ruler who ousted him in a military coup eight years ago.
Black-uniformed commandos entered the Pakistan International Airlines jetliner after it landed at Islamabad airport and surrounded Sharif, an Associated Press reporter on board said.
Sharif was refusing to hand over his passport to immigration officials who were also on the plane, the reporter said.
Before leaving London, Sharif warned that President Gen. Pervez Musharraf's government might try to arrest or deport him. At the last minute, he asked his brother Shahbaz Sharif to remain in Britain so that he can lead the party in case anything happens to the former prime minister.
Interior Ministry spokesman Brig. Javed Iqbal Cheema had said Sharif "would be treated according to the law" on his arrival. He declined to elaborate.
Supporters on the flight chanted "Go, Musharraf, Go!" as Sharif's flight taxied on the runway.
Pakistan's Geo TV network reported that the arrivals lounge of the airport had been evacuated. Other networks reported that phone jammers were in operation at the airport.
The arrival of Sharif, whose elected government was ousted by Musharraf in a 1999 coup, is likely to sharpen political tensions ahead of presidential and legislative elections.
The looming showdown could further weaken Musharraf's faltering grip on power and comes as the country battles surging Islamic extremism that has spread from the Afghan border, where Osama bin Laden and other al-Qaida leaders are believed to be hiding.
Around 200 supporters threw rocks at police preventing the crowd from reaching the airport, an AP reporter at the scene said. Officers fired off rounds of tear gas and hit people with batons. It was not immediately clear if anyone was seriously injured.
"We wanted to get to the airport to welcome the person who has challenged the dictator," said Asif Ali, one of the Sharif supporters. "We were tear-gassed and baton-charged."
In another clash on the main highway leading from the city to the airport, police beat and detained about 30 Sharif supporters, including his party spokesman, Ahsan Iqbal. They were bundled into a police pickup truck.
Former President Rafiq Tarar, a strong Sharif loyalist, said he was roughed up in that confrontation but not arrested. He declared the government was "anti-Pakistan." Witnesses said Tarar was later arrested.
After arriving in Islamabad, Sharif plans to travel in a motorcade to their home and political base in Lahore, about 180 miles to the south. The trip through Punjab province could take three days as he greets supporters along the way, Sharif's party said.More than 2,000 Sharif supporters in Punjab have been detained in a crackdown over the past four days, and others have gone into hiding, said Ahsan Iqbal, a spokesman for Sharif's party. Police and security officials, speaking on condition of anonymity because of the sensitivity of the issue, confirmed about 700 arrests.
On Sunday evening, a mobile squad swooped down on three buses carrying suspected Sharif supporters. Armed officers mounted each bus and ordered the drivers to take the passengers away - apparently into custody.
Analysts say Sharif's return could crank up the pressure on Musharraf and upset talks on a power-sharing pact with his longtime rival Benazir Bhutto, another exiled former premier plotting a political comeback.
Musharraf wants to win a new five-year presidential term from lawmakers by mid-October, while both Sharif and Bhutto want to contest general elections due by mid-January 2008.
Musharraf, who has received billions of dollars in U.S. aid to help in the country's fight against al-Qaida, has seen his popularity shrink since his failed attempt to fire Chief Justice Iftikhar Mohammed Chaudhry earlier this year spurred calls for an end to military rule.
Bhutto says she also plans to return to Pakistan, regardless of the outcome of the talks. She is due to announce her return date on Sept. 14.