ISLAMABAD, Pakistan — President Musharraf defied Pakistan’s Supreme Court yesterday, sending commandos to the airport and tossing out a bitter rival hours after he returned from exile in hopes of making a political comeback and opposing the military leader. The expulsion of Nawaz Sharif, who was ousted as an elected prime minister by General Musharraf in a 1999 bloodless coup, could deepen the general’s unpopularity and undermine the legitimacy of upcoming elections. Not long after he arrived from London to cheers from supporters accompanying him on the plane, Mr. Sharif was charged with corruption and money-laundering and bundled away by police from the airport VIP lounge. Four hours after landing, he was on a special flight to Saudi Arabia.

Pakistan’s deputy information minister, Tariq Azim, told the British Broadcasting Corp. that Mr. Sharif chose to go back into exile to avoid being detained and standing trial.

“It was a choice given to him that either he goes to a detention center and be detained and tried, or he goes and completes his 10-year [exile] agreement that he has signed with the Saudi government,” Mr. Azim told the BBC in an interview, according to an except provided ahead of its broadcast last night. “No hindrance or obstacle was placed upon his entry into Pakistan. He came here and he was given every assistance.”

Mr. Sharif’s unceremonious departure from the country where he had been exiled in 2000 scuttled his plans for a grand homecoming to campaign against the American-allied General Musharraf’s bid for election to a new presidential term amid growing public resentment over military rule.

“Musharraf has probably taken a decision to twist any law to do what he can do to stay in power. This is the politics of survival,” said Rasul Bakhsh Rais, a political scientist at Lahore University of Management Sciences. “He is relying on strong-arm tactics, not the law and the constitution.”

The deportation drew criticism from the European Union, which noted the Pakistani Supreme Court ruled last month that authorities had no right to block Mr. Sharif’s return.

The American government, which has valued General Musharraf as an anti-terrorism ally since the September 11, 2001, attacks, had a more guarded reaction.

A State Department spokesman, Sean McCormack, said the deportation “runs contrary to the Supreme Court decision.” But he declined to comment further, saying the “matter is still under legal consideration.”

In other Pakistan-related news, a California man was sentenced to 24 years in federal prison yesterday for attending an Al Qaeda training camp in Pakistan and plotting to attack targets in America.

Hamid Hayat, an American citizen who turned 25 yesterday, was convicted in April 2006 of providing material support to terrorists and lying about it to FBI agents. Prosecutors said he intended to attack hospitals, banks, grocery stores, and government buildings.