Shakib, 37, claimed nine wickets for Surrey in a thrilling Championship clash with Somerset at Taunton in September, his first appearance in the competition since a brief stint with Worcestershire in 2010-11.
As a left-arm spinner, he had agreed to a short-term deal to shore up Surrey’s resources for their title push, at a time when eight players were absent on England duty, including both of their frontline spinners, Will Jacks and Dan Lawrence.
He bowled more than 63 overs in the fixture, and though he was not no-balled at any stage for throwing, it has now emerged that the on-field umpires, Steve O’Shaughnessy and David Millns, subsequently deemed his bowling action to be suspect.
He is not suspended from playing, but ESPNcricinfo understands that negotiations are ongoing for Shakib to undergo further tests in an approved location, with the expectation that this will occur within the next couple of weeks.
It is thought to be the first time that Shakib’s bowling action has come under any scrutiny, in a career that has spanned two decades, and featured a total of 712 wickets across 447 international matches, including 246 in 71 Tests.