United Kingdom, April 21 -- Tim Cook is to step down as Apple CEO.

Cook, who first joined the tech company back in 1998 and has been CEO for the past 15 years after taking over from the firm's late co-founder Steve Jobs, will take up the role of executive chairman at the California behemoth.

He will remain in his current role until September 1, when he will be replaced by John Ternus - the current head of Apple's hardware engineering department.

Apple says that Cook will "assist with certain aspects of the company, including engaging with policymakers around the world".

Cook's decision to step down from his post follows months of speculation that Apple - which recently celebrated its 50th anniversary - was searching for a successor to...