The wife of the murdered Greek ambassador to Brazil has been jailed after being accused of masterminding his killing in a suburb here.

A Rio court on Saturday ordered Francoise Amiridis, the 40-year-old Brazilian to be placed in provisional custody for 30 days. She had been married to Kyriakos Amiridis for 15 years and they had a 10-year-old daughter, Xinhua news agency reported.

Rio police said she had been jailed in a feminine wing of Bangu prison, the largest in the city.

Francoise was arrested on Friday, along with a policeman who has an affair with Francoise and is suspected of having murdered the ambassador.

The policeman's cousin was also arrested for involvement in the case.

They confessed Francoise offered them 80,000 reais ($24,400) for the murder.

Kyriakos Amiridis, 59, was found dead in a burnt car below a bridge in Novo Iguacu, a northern suburb of Rio, on Thursday.

Greece's Foreign Ministry on Saturday said the death of Amiridis was tragic.

"We express our deepest sorrow at the tragic death of ambassador Amiridis who throughout his diplomatic career served Greece conscientiously and responsibly," the ministry said in a statement.

The 59-year-old diplomat assumed duties as Greece's ambassador to Brazil in January 2016. He had served in Rio de Janeiro as consul from 2001 to 2004, it said.