Akhtar and Asif launched successful appeals earlier this month after a tribunal in November banned them for two years and one year respectively for testing positive for the banned steroid nandrolone.
The new-ball pair could still be stopped from playing after the World Anti-Doping Agency (WADA) last week decided to challenge the lifting of the ban in the Court of Arbitration of Sports (CAS) in Switzerland.
But the Pakistan Cricket Board (PCB) insisted the doping matter was closed and Akhtar and Asif were free to play, with chief selector Wasim Bari saying Akhtar and Asif would be selected on the basis of fitness.
"We have no specific instructions about Akhtar and Asif and we think both are available for selection, so their fitness will be judged in the camp," Bari told AFP.
Bari said the same 25 would likely be part of Pakistan's World Cup plans.
"We have our 15 players in mind for the World Cup and these players more or less will be part of the World Cup team," said Bari of next year's World Cup in the West Indies.
The 31-year-old Akhtar featured in a four-day first-class match which ended here on Monday while Asif, who turns 24 on Wednesday, was scheduled to play the domestic Twenty20 championship starting here from December 21.
Akhtar played the last of his 42 Tests for Pakistan in January this year before missing Pakistan's Test series against England in July-August.
Asif played the last of his five Tests in April this year.
Both Akhtar and Asif missed Pakistan's home series against the West Indies due to their suspensions for doping. Pakistan won the Test series 2-0 and the one-day series 3-1 last week.
The pair were banned on Nov 1 after being sent home from the Champions Trophy in India. An appeals committee overturned the bans this month on the grounds that they were not sufficiently informed about doping issues.
Also recalled to the initial squad is fast bowler Shabbir Ahmed who was banned for one year for an illegal bowling action. Ahmed, whose ban expires on Tuesday, was cleared by biomechanic experts in Australia.
However, his selection will be subject to clearance by the International Cricket Council.
Pakistan will fly to South Africa on January 3 to play three Tests and five one-day internationals.
Pakistan Sunday retained Inzamam-ul-Haq as their captain until the World Cup in March-April next year.
Imran Farhat, Mohammad Hafeez, Yasir Hameed, Salman Butt, Younis Khan, Mohammad Yousaf, Inzamam-ul-Haq, Shoaib Malik, Faisal Iqbal, Asim Kamal, Abdul Razzaq, Kamran Akmal, Danish Kaneria, Abdul Rehman, Shoaib Akhtar, Mohammad Asif, Shahid Nazir, Rana Naved-ul-Hasan, Umar Gul, Mohammad Sami, Rao Iftikhar, Shahid Afridi, Zulqarnain Haider, Yasir Arafat and Shabbir Ahmed