Mahmud has been a revelation at Canterbury, taking 26 wickets across his four County Championship appearances, propelling Kent to third in Division Two. He also picked up four dismissals in the Vitality Blast.
Kent sit two points behind Northamptonshire, who occupy the last remaining promotion place. Durham have already secured their return to Division One as champions.
Mahmud is part of the squad for Bangladesh’s Asian Games quarter-final on September 28. He will then look to feature in Tests against Afghanistan and West Indies, followed by a three-format tour of South Africa.
“We’re disappointed to have lost Hasan’s services for the County Championship run-in,” said Kent’s director of cricket, Simon Cook. “But we respect the decision made by the BCB after constructive talks, and wish him well this winter.
“Everyone at the club thanks Hasan for his services the season, after taking 30 wickets in seven appearances across the Rothesay County Championship and Vitality Blast.”
Kent reiterated that fellow overseas seamers Keith Dudgeon and Khaled Ahmed remain available for their last two matches of the season. Both fixtures are at home against the two bottom-placed sides, Lancashire (starting on Tuesday) and Gloucestershire.