KARACHI - Pakistan cricket authorities Saturday demanded the England and Wales Cricket Board (ECB) explain what disciplinary measures have been taken against Stuart Broad after he made a twitter jibe about the legitimacy of spinner Saeed Ajmal's action.

Subhan Ahmed, chief operating officer of the Pakistan Cricket Board (PCB), said a letter had been sent seeking information on the situation. "Yes, we have written a letter to the ECB asking them what action they have taken against Broad for comments he has made against Ajmal," Ahmed told AFP.

"These comments are distressing for Ajmal who is upset and wants the ECB to take action," he added. Ajmal's agent Umran Khan said he has also taken up the matter, requesting "clarification" on the issue in a formal letter to the cricket authorities for England and Wales. As an England centrally contracted player Broad can be penalised by the ECB if he is found to have made derogatory comments about his fellow professionals.

Pakistan spinner Ajmal also currently plays for English county Worcestershire. He took 13 wickets in the Midlands side's recent County Championship win over Essex, including a career-best seven for 19 in the second innings. This prompted former England captain Michael Vaughan to ignite the row by posting a still photograph of Ajmal bowling during the match on Twitter. He added the caption: "You are allowed 15 degrees of flex in your delivery swing.... #justsaying."

Broad, currently out with a knee injury, replied by commenting: "This has to be a fake photo?!". He then commented: "Bowlers can bowl very differently in a lab while being tested compared to needing wickets in the middle." Ajmal's action -- reported for being suspect in 2009 -- has undergone extensive testing and been passed by the International Cricket Council (ICC).

Under the ICC rules bowlers are allowed to straighten their arm in delivery by up to 15 degrees. However, English cricket has long been suspicious of 'mystery' spin and innovations such as the 'doosra' (other one) whereby an off-spinner bowls a delivery that turns away, rather than towards, a right-handed batsman. Regarded as one of the best spinners of modern times, the 36-year-old Ajmal has so far played 33 Tests, 110 one-day internationals and 63 Twenty20 matches. He took 24 wickets in helping Pakistan rout then-world Test number one England 3-0 in their series in the United Arab Emirates in 2012.