Nov 18 (Reuters) - The CEO of an independent British oil

producer which is buying North Sea assets owned by Shell

and Exxon Mobil ( XOM ) is being sued by his former

employer for allegedly forging documents to steal substantial

sums.

Viaro Energy CEO Francesco Mazzagatti is accused by

Singapore-based company Alliance Petrochemical Investment of

being involved in the misappropriation of at least 143.8 million

euros ($151.5 million), court filings show.

The lawsuit, which was first reported by the Financial Times

newspaper, was filed at London's High Court in August.

Mazzagatti, who was previously chief executive of Alliance

Petrochemical Investment, denies the allegations and he and his

co-defendant, Francesco Dixit Dominus, Viaro's finance chief, in

their written defence deny misappropriating any funds.

Viaro Energy did not immediately respond to a request for

comment.

Viaro Energy said in July that it would buy Shell and

Exxon's Southern North Sea assets and assume full ownership of

one of the largest and longest producing gas asset portfolios on

the UK Continental Shelf, subject to regulatory approval.

Viaro acquired RockRose Energy in 2020 and since then has

made several other deals in the British and Dutch North Sea. The

company produces around 30,000 barrels of oil equivalent per day

and has interests in over 30 fields, according to its website.

Alliance Petrochemical Investment alleges in its lawsuit

that "there is credible evidence to suggest that Mr Mazzagatti

used at least part of the misappropriated funds to acquire a

majority share in RockRose Energy".

Mazzagatti and Dixit Dominus denied that allegation in their

written defence. They also say the allegations are the subject

of separate litigation in England and Italy, which the

defendants are also defending.