Pakistan pace bowlers Shoaib Akhtar and Mohammad Asif have returned negative results for last week's out-of-competition drugs tests conducted by the Pakistan Cricket Board (PCB), an official told Reuters on Saturday.

"We have received the results of the urine samples collected from all 26 players last week and they have all tested negative," PCB director of communications Ehsan Malik said.

"Shoaib and Asif have cleared the tests which are part of our zero tolerance policy towards drugs in sports."

The tests were conducted during a training camp in Karachi ahead of next month's Twenty20 World Cup in South Africa, which is an International Cricket Council (ICC) event where players can be subjected to random dope tests.

Malik said the samples had been sent to the International Olympic Committee (IOC) accredited laboratory in Malaysia.

Shoaib and Asif both tested positive for he banned steroid nandrolone last year when the PCB held tests before the ICC Champions Trophy in India.

They were initially banned in November but an appellate panel of the board cleared them of the charges and lifted their suspensions.