Mohammad Hafeez has questioned the process of umpires calling bowlers for illegal flex actions. 

The Pakistan veteran has been sanctioned for having a flex of over 15 degrees three times in his international career, only this month returning from an ICC suspension.

Umpires are required to identify suspect actions with the naked eye before reviewing, and Hafeez believes officials are more lenient when it comes to calls on bowlers from certain nations.

"There are so many things influencing all this - it has a lot to do with the power of [some] boards and nobody wants to take them on," Hafeez told BBC Urdu. "Mostly there are soft corners and relations between people which no one wants to spoil.

"What I say is why not implement the rule and get every bowler in the world to go through [testing]. What's the difficulty in that?

"When match umpires called me, I went for my test only to find the flex was recorded up to 16, 17 and 18 degrees. I was surprised: how can anyone with the naked eye see flex from 15 to 16, when at times they are not able to call those whose flex is 25 and even 30-plus?

"So I have my doubts about this calling system. This is suspicious: why are match referees or on-field umpires not able to see those flexing up to 35 but me with 16 degrees?"