Akhtar has been suffering from knee and hamstring problems and Asif has an elbow injury, but the tainted pair was also living in the shadow of pre-tournament drugs tests ordered by Pakistan.

They will be replaced by Yasir Arafat and Mohammad Sami for the World Cup which starts in the Caribbean on March 13, with the side still reeling from the loss of all-rounder Abdul Razzaq with a knee injury.

"It is a huge blow," coach Bob Woolmer told a news conference with captain Inzamamul Haq. "But their injuries would have taken more time and we couldn't wait anymore."

"It is true that our chances have been hit badly by the absence of these two key bowlers, but we will have to show the kind of spirit and team unity which can win us a big event like the World Cup," he said.

Inzamam added: "This is not an ideal situation for us. We are leaving for the West Indies under tremendous pressure."

The decision brings an end to the saga that began in November when Akhtar was banned for two years and Asif for one year after they tested positive for the steroid nandrolone, initially ruling them out of the World Cup.

The bans were later overturned on the grounds that they took the substance unknowingly. The Court of Arbitration for Sport in Switzerland is due to hear an appeal against that decision by the World Anti-Doping Association in April.

Several newspapers here reported that private tests, carried out while Akhtar and Asif were having their injuries reassessed in England, revealed they still have the banned substance in their systems.

Another positive result in official tests could have made them liable for life bans.

"We never conducted private or secret dope tests. It is propaganda against Pakistan," Pakistan Cricket Board (PCB) chairman Naseem Ashraf told a news conference in Islamabad.

"Their withdrawal is primarily because of injuries. The injuries were serious and had the played their careers would have been in danger," he said.

PCB World Cup spokesman Pervez Mir issued a similar denial -- a day after saying that the pair had been given more time to prepare for fitness tests.

"Their withdrawal has nothing to do with doping. They were due to feature in dope tests once they regained full fitness but for us the chapter is now closed," said Mir, who represented Pakistan in the first World Cup in 1975.

The 31-year-old Akhtar has been beset by injury. He was forced to return home from Pakistan's tour of South Africa after tearing his hamstring following his 4-36 on the first day of the second Test at Port Elizabeth last month.

Asif, 24, had a recurrence of an elbow injury sustained last year.

"Their injuries will take another two weeks to heal so after consultation with Inzamamul Haq we have taken the final decision," Pakistan chief selector Wasim Bari told AFP.

"The Pakistan team is capable enough to deal with this critical situation."

Pakistan were due to fly out later Thursday to the Caribbean, where they play the West Indies in the opening match at Jamaica on March 13.

Inzamam said Pakistan had "shown in the past that through team spirit we can overcome any crisis situation. Mohammad Sami and Arafat may not be as good as Akhtar and Asif but they'll try their level best to make up for the loss."

He added: "We could not take the risk on Shoaib and Asif as the deadline was approaching. We had to take a decision.

"It's up to the available players now to show their mettle so that we can achieve the best possible results in the World Cup."

Meanwhile Reuters adds from Mumbai, Pakistan all-rounder Azhar Mahmood has been cleared to play in the World Cup as a replacement for injured Razzaq.

A statement from the International Cricket Council (ICC) on Thursday said its technical committee had approved the substitution.

REVISED SQUAD
Inzamamul Haq (captain), Younis Khan, Imran Nazir, Kamran Akmal, Mohammad Yousuf, Shoaib Malik, Azhar Mahmood, Umar Gul, Danish Kaneria, Mohammad Hafeez, Shahid Afridi, Navedul Hasan, Rao Iftikhar, Yasir Arafat, Mohammad Sami.