Three of the four men convicted in Pakistan of abducting and murdering US journalist Daniel Pearl have appealed against their life sentences.

We have said to the court that there is not even a single piece of evidence against the appellants to prove the offences

Raj Bashir, defence lawyer

A lawyer for Salman Saqib, Fahad Naseem and Sheikh Adil asked Sindh High Court to acquit the men because their convictions were based on flimsy evidence.

British-born militant Ahmed Omar Saeed Sheikh, guilty of masterminding the abduction and murder, is expected to appeal against his death sentence later this week.

Meanwhile, Mr Pearl's father has said the guilty verdicts against his son's killers prove Pakistan has the strength to subdue terrorism.

The majority of the Pakistani people condemn the murder and view Danny as a symbol of their country's long-standing problem with terrorism

Daniel Pearl's father, Judea

The sentences were a "collective moral statement of historical significance", Judea Pearl said in a letter published by the Wall Street Journal, the paper for which his son worked.

The four men were sentenced on Monday after a three-month trial held in closed session by an anti-terrorism court.

On Tuesday, prosecutors appealed against the life jail terms handed down to Saqib, Naseem and Adil, and asked for them to face the death penalty too.

Chief Prosecutor Raja Qureshi argued that all four should face the same punishment.

Lengthy appeals

Omar Sheikh must file his appeal at the High Court within seven days of Monday's verdict.

Daniel Pearl was lured to his death

While it is underway he will live on death row in the prison in the southern city of Hyderabad where the trial was held.

Defence lawyers have said the appeals, which could then be passed up to the country's Supreme Court, could take as long as a year to process.

There had been enormous international pressure on the Pakistani authorities to show results in the case.

But the trial has angered Islamic militants, who accuse Pakistan's Government of betraying them by abandoning the Taleban in Afghanistan and supporting the US after the 11 September attacks.

Evidence questioned

Mr Pearl, 38, was kidnapped in Karachi in January while researching Islamic fundamentalism.

Troops in Karachi and Hyderabad are on alert

A gruesome video of his murder was later sent to US officials in Karachi.

The prosecution's case appeared largely to rest on a confession by Omar Sheikh that he later retracted.

The court also heard evidence from a taxi driver who testified that he had seen him meeting Pearl at a Karachi restaurant the night he disappeared.

Omar Sheikh himself called the trial a "waste of time", and vowed revenge for his death sentence.

Security has been tightened in Karachi since the verdict was announced, with extra police posted at embassies, hotels and American fast food restaurants.