(Adds no immediate comment from Saipem, comment from Duque's lawyer, paragraphs 4, 5)
SAO PAULO, July 29 (Reuters) - Prosecutors in Brazil said on Wednesday former Petrobras executive Renato Duque had unfairly favored Italy's Saipem SpA on a contract for an undersea gas pipeline for the Lula and Cernambi offshore subsalt fields.
The accusations came in an emailed summary of charges against Duque, who is already on trial for corruption, and four other people in a price-fixing, bribery and political kickback scheme at Brazil's state-run oil firm.
Prosecutors said Duque accepted bribes from Saipem's representative in exchange for favoring the company in a 2011 auction for the pipeline contract. As director of services at Petroleo Brasileiro SA, as Petrobras is known, Duque was the senior executive responsible for contracting.
Saipem did not immediately have a comment. This was the first time that the Milan-based oilfield services company has been mentioned in the scandal, which prosecutors believe ensnared more than a dozen foreign firms.
Duque's lawyer Alexandre Lopes said the charges were completely unfounded and based on plea bargain testimony that could not be proven.
The 19-kilometer (11.8 mile )pipeline, which can carry 14 million cubic meters (494 million cu. ft.) of natural gas a day, is part of a series of lines that will link offshore oil fields in the Lula complex with Brazil's coast east of Rio de Janeiro.
The Lula and Cernambi fields are owned 65 percent by Petrobras, which is also the field operator, 25 percent by BG Group Plc and 10 percent by Portugal's Galp Energia SGPS SA.
BG is in the process being acquired by Royal Dutch Shell Plc. (Reporting by Caroline Stauffer, additional reporting by Jeb Blount; editing by David Gregorio and Matthew Lewis)