(Adds details of ruling, political background)
BRASILIA, Feb 14 (Reuters) - A Brazil Supreme Court justice rejected an injunction that sought to remove President Michel Temer's minister in charge of infrastructure investment, Wellington Moreira Franco, who has been named in a corruption investigation.
Justice Celso de Mello's ruling on Tuesday also allows Moreira Franco to keep his immunity from prosecution by lower courts. The injunction filed by a leftist opposition party sought to annul his appointment as cabinet minister, arguing that Temer was trying to shield him from prosecution.
Mello ruled that was not the case.
Moreira Franco was implicated during plea bargain testimony by a former executive of engineering conglomerate Odebrecht who is a defendant in the sweeping bribery and political kickback investigation known as "Car Wash."
The probe, centered around state-run oil company Petroleo Brasileiro, has already ensnared dozens of top government, political and corporate leaders over the past two years and could implicate many more, including Temer himself, as plea bargain testimony advances.
As a minister, Moreira Franco can only be charged before the Supreme Court, where a trial would drag out for months or years.
Had Moreira's appointment been blocked by the injunction, any investigation of his role in the corruption scandal would have been in the hands of anti-corruption Judge Sergio Moro, who has presided over the Car Wash cases.
Annulment of one of his closest aides would had been a serious blow to Temer's political standing as he strives to restore business confidence in an economy mired in a two-year recession.
Temer on Monday dismissed criticism that he promoted Moreira to shield him from prosecution and vowed to dismiss any minister indicted for corruption. Until the promotion, Moreira was Temer's top adviser charged with drawing Brazilian and foreign investment for infrastructure projects. (Reporting by Lisandra Paraguassú, Alonso Soto and Anthony Boadle; Editing by Sandra Maler and Dan Grebler)