Pakistan fast bowler Shoaib Akhtar [Images] was included on Thursday in a preliminary squad for this year's England [Images] tour after undergoing knee surgery.

The selectors also recalled pace bowler Mohammad Sami [Images] in a squad of 21 who will attend a training camp from May 25.

"All the players will have to prove their fitness in the camp before being considered for selection," Pakistan board official Saleem Altaf told Reuters. The final squad will be announced on June 9.

Shoaib, 30, has been out of action with a knee injury since February. He underwent knee surgery in Australia and also suffered a stress fracture in his back.

Sami was dropped during the home series against India.

The selectors have called up uncapped wicketkeeper Zulqarnain Haider and recalled opener Taufeeq Umar [Images] who last played in March, 2005, against India in Kolkata.

Altaf said Asif, Rana Naved and Afridi were exempted from attending the first phase of the camp as they were playing county cricket in England.

The squad: Inzamam-ul-Haq [Images], Salman Butt [Images], Imran Farhat [Images], Taufeeq Umar, Shoaib Malik [Images], Younis Khan, Mohammad Yousuf [Images], Faisal Iqbal [Images], Shahid Afridi [Images], Bazid Khan, Asim Kamal, Kamran Akmal, Abdul Razzaq [Images], Shoaib Akhtar, Danish Kaneria, Rana Naved-ul-Hasan, Mohammad Asif [Images], Rao Iftikhar, Mohammad Sami, Umar Gul, Zulqarnain Haider.