Harare:Sri Lankan off-spinner Muttiah Muralitharan has broken the world record for most number of Test wickets by overtaking Courtney Walsh's haul of 519 wickets. Murali claimed his 520th victim, M Nkala, on the third day of the first Test against Zimbabwe in Harare to become the most successful bowler in the history of Test cricket. Adjudged the best bowler of all time by Wisden, Murali has had a tumultuous career facing constant allegations against his bowling action. Records galore However, his record in Test cricket speaks for itself. He is the only bowler to take over 300 wickets at home turf and has 44 five-wicket hauls to his name, in addition to claiming 10 wickets in a match 13 times. His average of 5.83 is the highest among bowlers with more than 250 Test wickets. Also, Murali is the only bowler to have taken nine wickets in an innings twice. Controversial action However all those records have been tinged by the controversy about his bowling action. Murali was first called in 1995 in Australia. Three years later it was proved that his bowling creates an optical illusion of chucking because of a deformity in his elbow. The most recent investigations this year proved that his special delivery called the 'doosra', which spins away from a right-hander, is illegal because his arm bends at more than the permissible five degree limit.