Pakistan fast bowler Shoaib Akhtar on Friday proclaimed himself as a doubtful starter for next month's World Cup with his knee being still a matter of concern.

Shoaib, who spent the last week in London apparently to seek medical opinion on his knee problem, said he would again leave for the city on Sunday.

"The picture is not very good on the knee and I am going for another examination. But right now I can't say for sure I will be able to play in the World Cup," he told reporters at the Gaddafi stadium in Lahore on the first day of the team's training camp.

The 'Rawalpindi Express' said he is making every effort to be fully fit for the mega-event beginning on March 13 and does not know the status of his dope tests.

"I don't know right now when I will take the dope tests because at the moment the more important thing for me is to be 100 per cent fit for the World Cup," he added.

Shoaib also said he had sunk his differences with coach Bob Woolmer and their altercation reported during their recent Test series in South Africa is a thing of past.

"What happened in South Africa is now a thing of the past. I respect him as coach," he said.

Mohammad Asif, who had also tested positive for a banned substance with Shoaib last year, also showed up at the camp but could not confirm when he would take the tests.

He avoided speaking to the media insisting he was instructed by the Board not to say anything.

However, sources in the Board have indicated that both the bowlers are close to be ruled out of the World Cup.

They have had tests in London which have shown the level of the banned substance nandrolone has not come down substantially enough in their bodies for them to go to the World Cup without any fear of testing positive, the sources said.

The Board has constantly maintained the two went to London on private visits to get medical opinion on their injuries but now it appears they might have gone there for other reasons as well.

Medical experts say nandrolone remains in the body of an athlete for atleast six months after using it. The two had tested positive for the substance last October and were banned before being cleared by an appeals panel of the Board.