The chairman of the Pakistan Cricket Board (PCB) has called on umpires to clean up the problem of illegal bowling actions.

In a letter to all umpires, Shaharyar Khan asked them to report bowlers even if they had only a slightly doubtful action.

"I am writing to seek your assistance in checking the increasing instances of illegal bowling actions in Pakistan cricket at all levels," Khan wrote.

"We need to take corrective measures early to avoid embarrassment and to play our part in cleaning up illegal actions."

Pakistani cricket has faced problems with suspect bowling actions at international level.

Fast bowlers Shoaib Akhtar and Shabbir Ahmed have both been reported for suspect action.

Shoaib's action was cleared by biomechanics experts in Australia in 2002 while Shabbir underwent corrective work on his action in Perth earlier this year.

Other Pakistani bowlers reported to the International Cricket Council officials have included Shahid Afridi and Shoaib Malik.

Khan directed umpires to pinpoint possible offenders at an early stage so corrective measures could be taken before they reached a representative level at which questioning of their action would become embarrassing and contentious for Pakistan.

No bowler has ever been reported at domestic level for an illegal bowling action.