LONDON, March 5 (Reuters) - Britain dropped its probe

into Microsoft's ( MSFT ) partnership with ChatGPT maker OpenAI

on Wednesday, saying the software giant did not have the level

of control over the AI company that would warrant further

investigation.

The partnership came under antitrust scrutiny in Britain

and the U.S. last year following the startup's

boardroom

battle that led to the exit and

return

of CEO Sam Altman.

Britain's Competition and Markets Authority (CMA) said

although Microsoft ( MSFT ) did acquire material influence over OpenAI in

2019, it had not since gained de facto control and therefore it

did not qualify for review under the UK's merger control regime.

A Microsoft ( MSFT ) spokesperson said the partnership with

OpenAI and its continued evolution "promote competition,

innovation, and responsible AI development".

"We welcome the CMA's conclusion, after careful and

prudent consideration of the commercial realities, to close its

investigation," the spokesperson said.