Pakistan's Saeed Ajmal has been suspended by the International Cricket Council for an illegal bowling action.
The 36-year-old off-spinner was reported last month after match officials raised concerns during the first Test against Sri Lanka in Galle.
Analysis of Ajmal's action revealed that "all his deliveries exceeded the 15 degrees" by which the arm is allowed to bend, the ICC said.
Ajmal said he was disappointed, but added: "I know I can correct it."
He is currently the world's top-ranked one-day international bowler.
|Saeed Ajmal's international career in numbers|
|Statistics correct on 9 September 2014|
He also has 178 Test wickets, at an average of 28.10, and is still the leading wicket-taker in the County Championship this season with 63 in nine matches for Worcestershire, despite not having played for them in almost two months.
"An independent analysis has found the bowling action of Pakistan's off-spinner Saeed Ajmal to be illegal and, as such, the player has been suspended from bowling in international cricket with immediate effect," the ICC said in a statement.
Ajmal's action was analysed by an ICC-accredited team of human movement specialists using the National Cricket Centre in Brisbane, Australia, on 25 August.
"The ICC has stopped me from bowling because my elbow is bending beyond the 15 degrees allowed and I know I can correct that," Ajmal said.
"It is very disappointing to know the results of the tests, but I am a fighter and I know what I have to do to get back into international cricket before the World Cup."
The Pakistan Cricket Board (PCB) confirmed it was considering an appeal, but was more circumspect on Ajmal's chances of returning to the international arena.
PCB spokesman Agha Akbar told BBC Radio 5 live that Ajmal's chances of playing in the World Cup early next year are "bleak".
Asked if the ban could signal the end of the bowler's international career, Akbar said: "It looks like that."
|The ICC's clampdown on spinners|
|Shane Shillingford (West Indies)||Suspended in December 2013. Cleared to return in March|
|Sachithra Senanayake (Sri Lanka)||Suspended in July|
|Kane Williamson (New Zealand)||Suspended in July|
|Prosper Utseya (Zimbabwe)||Reported in August|
|Sohag Gazi (Bangladesh)||Reported in August|
The ECB told BBC Sport that the ban would extend to domestic competitions, preventing Ajmal from returning to county cricket.
"We're disappointed for Saeed," said Worcestershire chief executive David Leatherdale. "He was never reported while playing for Worcester.
"He will now have to go through the remodelling process like other cricketers have had to do before him.
"As regards next season, it's not something to be talked about while he goes through that remodelling process."
Ajmal, who made his international debut in July 2008, can apply for a re-assessment after he modifies his bowling action.
The ICC has recently taken action against several off-spinners.