Saeed Ajmal is to ask for an explanation from the ECB after Stuart Broad appeared to question the legality of the bowler's action.

Ajmal, who played a large part in Pakistan's whitewash Test series victory over England in the UAE at the start of 2012, is currently playing for Worcestershire as an overseas player in the County Championship. He claimed 13 wickets in their recent victory over Essex, including a career-best haul of 7 for 19 in the second innings.

That led to Michael Vaughan, the former England captain, posting a still photograph of Ajmal bowling during the game on Twitter with the caption "You are allowed 15 degrees of flex in your delivery swing.... #justsaying."

Broad then replied with the comment "This has to be a fake photo?!" before a further tweet stated: "Bowlers can bowl very differently in a lab while being tested compared to needing wickets in the middle."

Ajmal has concluded that this implied that the action he uses in a match situation is not the same as that used in testing. He has also concluded that the comments insinuate that his action may not be legitimate. He has instructed his agent to talk to the PCB and ECB about the comments and seek an explanation.

As a centrally contracted player, Broad is restricted in the comments he can make about fellow players and can be penalised if they are found to be derogatory.

It has long been known that Ajmal bowls with a bend in his arm. That is not against the playing regulations for international cricket, though, and after exhaustive tests, the ICC concluded that his arm did not straighten by 15 degrees and therefore declared his action legitimate.

As part of the ICC testing procedure, match footage is used alongside videos made "in a lab" and compared to ensure it is identical. Umpires are then able to copy TV footage of bowlers in action and super-impose them on the testing footage to check that a bowlers' action has not subsequently deteriorated. It is understood by ESPNcricinfo that the umpires involved in the Pakistan-England series in the UAE used this facility to check that Ajmal's action was the same as when it was tested. They found it to be identical.

Umpires in county cricket can report international bowlers to the ECB just as they would domestic bowlers should they have any doubts over their action.

The English game has long viewed 'mystery' spin with suspicion. While several other nations have embraced the unorthodoxy that has resulted in innovations such as the doosra, the vast majority of English spinners persist with the traditional methods in an environment that has become, with improved bats, more benign pitches and more aggressive batsmen, ever more hostile towards them.

The ECB also still utilise a different testing procedure to measure the legality of bowlers' actions to that used in international cricket. While they deny that their procedure is more stringent, the fact remains that very few unorthodox bowlers have emerged through the English system in recent years.

Moeen Ali can bowl the doosra - he has been taught it by Ajmal - but has yet to use it in international cricket. Previous English doosra bowlers either left the game early (Alex Loudon) or were warned against using the delivery (Maurice Holmes) and saw their career come to a premature end.