"We have clearance from the ICC technical committee to replace Shoaib Akhtar and Mohammad Asif," PCB director of cricket operations Saleem Altaf told Reuters, adding the replacements had left for the Caribbean and would join the team by Thursday.
The PCB withdrew Shoaib and Asif from their World Cup squad last Thursday on fitness grounds and submitted their medical reports to the ICC this week.
Shoaib (knee and hamstring) and Asif (elbow) have been initially advised to rest for three weeks.
Pakistan open their World Cup campaign against hosts West Indies on March 13.