The 48-year-old official, who famously no-balled Sri Lankan spinner Muttiah Muralitharan, reportedly received a threatening letter from an English-based supporter of a Tamil militant separatist group.

Part of the letter warned Hair that "we have representatives of our people throughout all major nations of the world and we will take action against you for what you have done", the Sydney Daily Telegraph reported.

Australian umpire Hair was thrust into the spotlight in 1995 when he called Muralitharan - Sri Lanka's most prominent Tamil cricketer - seven times for throwing.

Sri Lanka later insisted Muralitharan was physically unable to straighten his arm due to an anatomical defect he was born with - a view supported by the International Cricket Council.

Book row

The letter was postmarked from the English town of Harrow but left was unsigned.

Muttiah Muralitharan's bowling action has been heavily scrutinised

He received the threat shortly before leaving Australia and reported the letter immediately to the Australian Cricket Board and the ICC.

World Cup organisers have decreed that Hair will not officiate during any of Sri Lanka's matches, in an attempt to avoid further controversy.

He caused further uproar earlier this year when he published his autobiography and described Muralitharan's action as "diabolical".