Ahmed, is the first bowler to be banned from bowling in international cricket for 12 months after an independent assessment by the University of Western Australia (UWA) confirmed he bowled with an illegal action.
The finding comes after Ahmed was reported for the second time under the revised ICC bowling review regulations by the on-field umpires Simon Taufel and Billy Bowden and TV umpire Asad Rauf during the first Test against England in Multan in November.
He was first reported and suspended earlier this year but returned to international cricket following remedial work on his action and a full bio-mechanical analysis that demonstrated that he had made the necessary adjustments to his bowling style.
Having been reported and assessed as bowling illegally for a second time within two years of the first period of suspension, Ahmed has received a mandatory one-year ban.
His team mate, Shoaib Malik, was reported for the first time under the revised ICC regulations in the same match against England and travelled to the University of Western Australia to undergo independent laboratory bio-mechanical analysis.
He was able to show that the bowling action he used in the match and in the laboratory falls within the ICC regulations. He has been advised that, provided he employs an action consistent with that used in the laboratory, he can continue to bowl in international cricket.
In his latest report on Ahmed's action, Professor Elliott concludes that it is likely to be illegal.
"It could therefore be concluded, given Mr Ahmed's current level of maximum elbow flexion, that he probably bowls some deliveries in each innings that are above the acceptable 15 degree tolerance limit as stated in the September 2005 report ," Professor Elliott's report says.
ICC Chief Executive Officer, Malcolm Speed, said Ahmed's suspension was an appropriate step.
"While it is regrettable that any player is suspended from international cricket, the suspension is an appropriate step on this occasion," he said.
"It is clear that Mr Ahmed has the capacity to bowl with a legal action but it would seem that on occasion he has the tendency to revert to old habits.
"Having had the opportunity to remedy this flaw but not being able to do so consistently, a suspension for 12 months provides him with the opportunity to permanently address the concerns that have been identified.
"At the same time, it indicates the ICC's seriousness in tackling this issue."
The current process contrasts with previous eras where once a bowler was called for throwing or was suspected of having an illegal action there was often no way back to international cricket.
"I hope that Shabbir will be able to use his time out of the game at international level to get the consistency needed in his action to ensure a successful return to the game," said Speed.
The latest assessment of Ahmed's action was based on examination of footage from the Multan Test in comparison with a University of Western Australia (UWA) laboratory assessment, which he underwent in September.
The ICC and the PCB agreed to this as an alternative to submitting Ahmed to another assessment.
Ahmed can appeal to the ICC's specialist Bowling Review Group to seek to overturn the ban. He must lodge a request for such a hearing within 14 days of the PCB's receipt of the assessment of his action.
The analysis of Malik's action notes that only Malik's off-break delivery was assessed based on his direction that this was the only delivery that he has bowled in the Multan Test and other recent international cricket.
Should he revert to bowling the 'doosra' delivery or should his action deteriorate - as with any bowler - it is possible that he could be reported again or be called. If such a situation arose, Shoaib would be expected to undergo further independent analysis of his action.