Former Australian Test quick Jason Gillespie has resigned as Pakistan's red-ball coach, with another ex-fast bowler Aqib Javed taking over in an interim capacity.

The 49-year-old Gillespie had been signed up by the Pakistan Cricket Board on a two-year contract back in April alongside South African Gary Kirsten, who resigned as limited-overs coach in October.

Gillespie resigned on Thursday amid media reports of a breakdown in relations between him and the PCB.

Aqib, who was appointed Pakistan's interim white-ball coach last month, will now also take on red-ball coaching duties.

"Aqib's first assignment as red-ball head coach will be the two-match Test series against South Africa during the ongoing all-format tour," the PCB said in a statement.

Pakistan are in South Africa playing a three-match Twenty20 international series followed by three one-day games, before the first Test begins in Centurion on December 26, and the second in Cape Town on January 3.