Zahira Sheikh told a court in Mumbai (Bombay) that she had had no clear view of what happened during the attack.

The Supreme Court ordered the retrial after Ms Sheikh said her testimony in the first trial followed threats, but she backtracked again last month.

At least 1,000 people, mainly Muslims, died in Gujarat's Hindu-Muslim riots.

The so-called Best Bakery case was one of the most notorious acts of violence during the riots.

Twelve Muslims and two others were burnt to death when the bakery was attacked, allegedly by a Hindu mob, in the town of Baroda.

Zahira Sheikh's testimony is considered central to the prosecution case, and legal experts say her failure to identify the accused will make it difficult to secure convictions.

Hostile witnesses

In all six witnesses, among them Ms Sheikh's mother and two brothers, have now refused to identify those in the dock in Mumbai.

In earlier statements to the police they had all named the accused as being responsible for the Best Bakery killings.

The first trial in Gujarat collapsed in similar circumstances. Witnesses retracted evidence in court and the 21 defendants were freed.

Seventeen of the men are being tried again. The other four have absconded.

Zahira Sheikh has now twice changed her story.

After the first trial, she said members of the Hindu nationalist Bharatiya Janata Party (BJP) had bullied her into altering her evidence.

That prompted the Supreme Court to order a fresh trial in Maharashtra state.

But last month, with the retrial under way, Zahira Sheikh told a news conference she had been pressured into accusing the BJP by a human rights group, Citizens for Justice and Peace.

The group angrily rejected the claims and petitioned the Supreme Court, which has ordered Zahira Sheikh to explain her change of statements.

'How could I see?'

Giving evidence on Tuesday, she said she was unable to recognise the accused.

She told the court that she was on the terrace of her family home with relatives as the bakery was being attacked.

"We were scared," she said, "from all four sides there were stones and bottles being thrown at us."

Her sister, Sabira, was killed in the violence. When asked who was throwing the stones, Zahira Sheikh said that she did not know.

"It was dark and there was smoke. So how could I see?"

Last month, Ms Sheikh's sister-in-law, Yasmin Sheikh, testified that Zahira changed her statement after accepting bribes.

A court is looking into the sources of her funding.

The 2002 riots left a deep scar on the Muslim minority in Gujarat, many of whom still say they live in fear.

The Best Bakery case is often cited by human rights groups as evidence that riot victims have gained little justice.