A landmark trial arising from attacks on Muslims that swept the state of Gujarat in 2002 was thrown into turmoil Wednesday when the government's star witness accused a human rights activist of forcing her to make false accusations against Hindu defendants in the case.

Zahira Sheikh, a young Muslim woman, had been scheduled to take the witness stand Thursday in the case against 21 men accused of attacking her family's bakery in the town of Vadodara and killing 14 of her relatives and neighbors during communal violence that claimed the lives of more than 1,000 people.

But on the eve of her testimony, Sheikh accused Teesta Setalvad, a prominent human rights campaigner, of holding her captive for seven months and threatening to kill her if she did not falsely identify the accused men. Sheikh made the charge at a nationally televised news conference.

Sheikh also accused Setalvad of forcing her to sign statements naming the accused in English, a language she does not understand. "Teesta used me like a toy," Sheikh said. "She took my signatures against my wishes several times."

Setalvad did not return messages left at her home and on her cell phone Wednesday night. But in an interview with the Aajtak television news channel, she called the charges "completely baseless" and suggested that Sheikh had come under pressure from associates of the defendants to recant -- the second time she has done so in the case.

The Gujarat bloodletting began when a Muslim mob set fire to a train carrying Hindu nationalists on Feb. 27, 2002, killing at least 58 people. That attack sparked a wave of anti-Muslim violence that human rights investigators say was aided by Hindu nationalist politicians in the state government.

The case involving Sheikh dates to the night of March 1, 2002, when men wielding swords and plastic bags filled with gasoline laid siege to the Sheikh family's Best Bakery and adjacent home. In the immediate aftermath of the attack, whose 14 victims included Sheikh's sister and an uncle, Sheikh identified seven of the attackers by name. But the case against them collapsed in May 2003, when Sheikh changed her testimony on the witness stand and said she could not identify the attackers.

A few months later, Sheikh resurfaced at a news conference in Bombay -- arranged by Setalvad's human rights group -- and asserted that she had lied on the witness stand because of threats from state politicians.

Sheikh's story caused an uproar in India, where human rights campaigners seized on the case as a symbol of the state government's failure to aggressively prosecute those responsible for the anti-Muslim violence.

Last spring, the Supreme Court described state officials as "modern-day Neros" and ordered a retrial in Bombay, the capital of the state of Maharashtra. Sheikh's story inspired a Bollywood movie.

But Sheikh says her original courtroom testimony, in which she said she was unable to identify her attackers, was correct. She changed her story, she said Wednesday, because Setalvad and her colleagues "threatened to kill me."

Sheikh's motive in changing her testimony now is the focus of considerable speculation in the Indian media. Television reports noted that she held her news conference in a five-star hotel and that the Gujarat police had taken the unusual step of granting her request for police protection.