Police detained supporters of former Prime Minister Nawaz Sharif and sealed off the airport ahead of his return Sunday from exile, a reminder that President Gen. Pervez Musharraf's emergency rule remains in effect.

Sharif was due in the eastern Pakistani city of Lahore later in the afternoon, flying back with his wife and brother on a plane provided by King Abdullah of Saudi Arabia, the country where Sharif has spent most of the past eight years since Musharraf overthrew him in 1999. The king also provided a bulletproof Mercedes for the family.

Ahsan Iqbal, a spokesman for Sharif's party, said some 1,800 activists were detained in a crackdown since late Saturday in Punjab province, of which Lahore is the capital.

However, federal Information Minister Nisar Memon said he was exaggerating.

"There are no arrests as such," Memon said. "About 100 people have been confined so that they do not create any issues. We don't want the same mess as there was in Karachi."

He was referring to the huge rally that greeted another former premier, Benazir Bhutto, when she was allowed to return to Pakistan last month. Her homecoming procession was torn by a suicide bombing that killed about 150 people.

Both Bhutto and Sharif are seeking to return to power after Jan. 8 parliamentary elections. But the ballot, which the West hopes will produce a moderate government able to stand up to Islamic extremism, has been thrown into confusion by Musharraf's Nov. 3 seizure of emergency powers.

Memon said leaders of Sharif's party would be allowed to greet him Lahore's Allama Iqbal International Airport and drive with him into the city.

But Sharif's entourage was suspicious.

"The police action and massive deployment shows that something fishy is going on. They've blocked every single vehicle carrying supporters of (Sharif's party)," said Sayed Hafeezuddin, a lawyer for the exiled leader.

Thousands of police were deployed at the airport, some of them guarding metal and barbed-wire barriers on approach roads and sidewalks. Passengers with tickets were allowed through.

On the streets of the city, several welcome posters and banners of Sharif were on display, but there was no sign of supporters gathering to greet him.

Authorities have issued no warnings that Islamic militants bitterly opposed to Musharraf and Bhutto for their pro-U.S. police might target the more conservative Sharif.

However, his arrival comes one day after homicide bombers killed up to 35 people in nearly simultaneous blasts at the heart of Pakistan's security establishment in Rawalpindi, a garrison city adjacent to the capital, Islamabad.

It was not clear who was behind the explosions — which targeted a bus carrying intelligence agency workers and a checkpoint near army headquarters — but authorities said suspicion rested on Islamist militants who are fighting an increasingly bloody insurgency against government troops in the northwest of the country.

The army said Sunday that 30 pro-Taliban fighters and one Pakistani soldier died in an operation to capture militant positions in the Swat valley, a former tourist destination just 160 kilometers (100) miles from Islamabad.

Musharraf cited rising religious extremism as a reason for his declaration of a state of emergency. However, many of those targeted under the crackdown have been political opponents, lawyers and members of the media.

More than 5,500 people have been detained since the crackdown began, but authorities insist virtually all have been freed since last weekend, when visiting U.S. Deputy Secretary of State John Negroponte urged Musharraf to restore the constitution.

Sharif's return could prove challenging for Musharraf, particularly if the former prime minister makes an alliance with Bhutto and the two boycott the Jan. 8 elections. But it is also a potential boon for the general, allowing him to claim that he favors a genuine return to democracy.

After Musharraf overthrew Sharif, he gave the jailed politician a choice: Accept 10 years of exile or face life in prison on charges including hijacking and terrorism. The charges stemmed from Sharif's desperate attempts to turn away a packed civilian plane carrying Musharraf — then the army chief — back from a trip abroad.

As the Pakistan International Airways plane ran low on fuel, Musharraf used the cockpit radio to contact his senior commanders on the ground, who quickly took over the country. By the time the plane touched down in the southern city of Karachi, Musharraf was Pakistan's new leader and Sharif was under arrest.

Sharif has been angling for a return ever since. In September he boarded a flight from London to Islamabad, but police in the Pakistani capital swiftly booted him back to Saudi Arabia.

This time, the outcome is likely to be different, with the Saudi leadership reportedly pressuring Pakistan to accept him.

"This time he will not be sent back," said Sheikh Rashid Ahmed, a former Cabinet member and close adviser to the general.

Major opposition parties — including Bhutto's Pakistan People's Party — have been lining up to take part in the ballot, taking preliminary steps such as filing nomination papers. Bhutto said Friday she had not yet decided whether to take part, but that she was leaning toward participating.

On Saturday, a loose coalition of opposition groups including Sharif's PML-N announced it would boycott the voting unless the government lifts the state of emergency, restores sacked Supreme Court justices and releases all political prisoners within four days.