UPDATE 3-WPP goes into open conflict with former CEO Sorrell

* WPP refuses to pay ex-CEO Sorrell's share awards

* WPP alleges Sorrell leaked to the media

* Sorrell says the move is "petty"

* Sorrell says his lawyers will look at it
(Recasts headline and lead)

By Kate Holton

LONDON, April 29 (Reuters) - WPP, the world's
biggest advertising company, launched into open conflict with
its founder Martin Sorrell on Thursday, refusing to pay share
awards and accusing him of leaking client information to the
media.

In a twist that pits WPP against the world's most famous
advertising executive, the British firm said a long-term
incentive share scheme would lapse after it found the former CEO
had leaked confidential details while he was running the firm.

The 76-year-old Sorrell, now running fast-growing digital
challenger firm S4 Capital, denounced the move,
describing it as petty and motivated by anger at his success.

"It’s a bit rich that they’re accusing me of leaks, given
their own over the last three years," Sorrell told Reuters.

"They’ve had to go back several years to try and find an
excuse to deny me what’s mine. I’ve left it to my lawyers to
deal with," Sorrell said.

Sorrell, the most famous advertising boss of his generation,
built WPP into the world's biggest advertising company through a
string of major deals over three decades to offer advertising,
media buying services, public relations and data analytics to
global brands such as Ford, HSBC and Unilever.

In the process he became one of Britain's most high-profile
businessman, mingling with politicians and presidents around the
world.

He left the British firm in 2018 over a complaint about
personal misconduct which he has always denied. His new firm has
a market value of 3 billion pounds ($4.2 billion) and a large
roster of clients.

WPP, now led by the one-time Sorrell protege Mark Read, said
in its annual report that its compensation committee had
exercised its discretion to deny giving the former CEO share
awards from a 2016 and 2017 scheme.

It said the decision was made due to "Sir Martin Sorrell’s
disclosure of confidential information belonging to WPP and
certain of its clients to the media during his tenure as a WPP
director."

WPP published a trading update on Wednesday that showed the
goup had returned to organic quarterly growth for the first time
since the third quarter of 2019. Sorrell's S4 reports next
Tuesday.
($1 = 0.7169 pounds)
(Editing by Guy Faulconbridge, Kirsten Donovan)