TORONTO, Aug 16 (Reuters) - Royal Bank of Canada ( RY )

filed a countersuit against ousted CFO Nadine Ahn on Friday,

detailing findings of its internal investigation into her

alleged intimate relationship with a subordinate, and accusing

her of breaching its code of conduct.

Ahn sued RBC last week for wrongful termination and alleged

that "gender-based stereotyping" was a factor in her dismissal.

She has sued RBC for nearly C$50 million ($36.56 million).

In April, RBC, Canada's biggest bank, said it had terminated

Ahn after its investigation found she was in an undisclosed

close personal relationship with another executive, Ken Mason,

that led to his preferential treatment including promotions and

compensation increases.

Mason has also sued the bank for about C$20 million for

wrongful termination and has denied any close personal

relationship with Ahn.

In its statement of defense and counterclaim filed with the

Ontario Court of Justice, RBC said it received an anonymous

whistle-blower complaint that Ahn and Mason were engaged in an

intimate relationship.

RBC said it reviewed electronic communications maintained on

its systems and found through its investigation that Ahn and

Mason regularly used personal and work devices to communicate.

The court filing detailed Ahn and Mason's relationship

starting in 2013 or earlier, highlighting their dates, poems

written by Mason, intimate email exchanges and what the bank

said was code they used to describe meeting for drinks.

RBC said Ahn should repay RBC about C$3.3 million for

payments related to its performance-based deferred share unit

program, short-term incentive program and gains on the exercise

of RBC stock options.

Ahn's intervention led to Mason receiving total compensation

increases amounting to 58% over two fiscal years starting in

2021, and she made the decision to promote Mason as vice

president and head of capital and term funding in 2023, the bank

said.

Lawyers for Ahn, 53, and Mason, 57, did not immediately

respond to requests for comment on the countersuit.

In her wrongful termination lawsuit, Ahn said the bank's

allegations were "patently false" and her successes, career and

reputation were destroyed in an instant by the bank.

A spokesperson for RBC said on Friday it had been

disappointed to learn the allegations were true. Ahn was a

"highly respected member" of the executive team with fiduciary

responsibilities and the bank had "great confidence in her

abilities," the spokesperson said.

"Contrary to the statements of claim from Ahn and Mason, the

investigation showed there was an undisclosed close personal

relationship, and that Ahn misused her authority as CFO to

directly benefit Mason," the spokesperson said in a statement,

adding that all senior executives have a duty to follow its code

of conduct.

($1 = 1.3676 Canadian dollars)

(Reporting by Nivedita Balu in Toronto; Editing by Daniel

Wallis and Muralikumar Anantharaman)