(Adds details on proposed project, background)
SAO PAULO, Aug 12 (Reuters) - Engineering groups Odebrecht and Queiroz Galvao said on Wednesday they are pulling out of a consortium building a nuclear reactor in Brazil due to payment delays from Eletronuclear, a unit of state utility Eletrobras.
The Angra 3 project was designed to become Brazil's third nuclear power plant, but it has faced multiple delays over the years since plans for the reactor were first drawn up in the 1980s.
Construction restarted in 2010, but the arrest last month of two key executives, including Eletronuclear's former chief executive officer Othom Luiz Pinheiro da Silva, has again raised doubts about the project's completion.
Federal prosecutors said Pinheiro da Silva received 4.5 million reais ($1.3 million) in bribes from other companies participating in the construction.
Odebrecht and Queiroz Galvao are also targets of a broader corruption investigation surrounding state-controlled oil company Petroleo Brasileiro, but not related to their activities at Angra 3.
Eletrobras said it would probably comment later in the day about the decision from the companies to leave and their allegations of payments delays. (Reporting by Luciano Costa; Writing by Marcelo Teixeira; Editing by Bernard Orr)