ROME (Reuters) - Prosecutors in Rome have opened an investigation into four executives at Swiss drugmakers Roche (>> Roche Holding Ltd.) and Novartis (>> Novartis AG) on suspicion of fraud and manipulation of the pharmaceutical market, judicial sources said on Friday.

The sources did not name the managers.

Earlier this month, Italy's antitrust authority said Roche and Novartis colluded to try to stop cancer drug Avastin from being used to treat a serious eye disease and fined the companies 182.5 million euros (152.8 million pounds).

Italy's regulator accused the two Basel-based firms of striking an alliance to prevent distribution of Roche's Avastin as a treatment for wet age-related macular degeneration (AMD) in favour of the more expensive drug Lucentis made by Novartis.

A Novartis spokesman had no immediate comment on Friday.

Roche issued a statement saying it had not been informed by prosecutors that any of its managers were under investigation.

"Roche reiterates that it has acted correctly and confirms its confidence in the fact that this will be fully recognised," it said.

It also confirmed that it would appeal against the anti-trust ruling to an administrative court, as it said when the ruling was issued.

Novartis has also strongly denied the regulatory decision and pledged to appeal.

(Reporting by Mario Sarzanini in Rome and Caroline Copely in Zurich; Writing by Steve Scherer; Editing by Erica Billingham and Sophie Walker)

Stocks treated in this article : Roche Holding Ltd., Novartis AG
Valeurs citées dans l'article : Novartis AG, Roche Holding Ltd.