(Adds comments from companies)
SAO PAULO, April 1 (Reuters) - Another five Brazilian construction and engineering firms have been added to an investigation of contractors that allegedly participated in a corruption ring at state-run oil company Petrobras, the office of the comptroller general said on Wednesday.
The companies include Techint Engenharia e Construções Ltda, NM Engenharia e Construções Ltda, Construcap CCPS Engenharia e Comércio SA, Niplan Engenharia SA, and Jaraguá Equipamentos Industriais Ltda, the agency known as CGU said in a statement.
Twenty-nine of Brazil's top builders are under investigation for suspected overpricing of contracts in a multibillion-dollar scheme that funneled bribes to Petrobras executives and politicians.
The case may exclude the companies from new contracts with Petroleo Brasileiro SA, as the oil company is formally known, and lead to fines and other penalties.
NM Engenharia said in a statement it would cooperate with authorities, had not previously been investigated, and lamented being tied to the situation after 35 years of serving Petrobras.
Niplan said it had "never practiced any type of illegal act in its commercial relations."
Techint said it would clarify any doubts when it presents its defense. Construcap denied participating in any price-fixing cartel and said it would cooperate with authorities.
A representative of Jaraguá Equipamentos Industriais could not be reached for comment. The CGU said it may still expand the investigation to cover more companies.
Brazil's biggest-ever corruption scandal is rippling through various sectors of the national economy, threatening to stall major infrastructure projects as so many engineering firms come under investigation. (Reporting by Brad Haynes and Marta Nogueira; Additional reporting by Jeferson Ribeiro in Brasilia Editing by W Simon; Editing by Richard Chang)