Just three days after taking office, the new director of Brazil's federal police force, Joao Batista Campelo, has resigned amid allegations that he participated in the torture of political prisoners during the 1970s.

In a short letter to President Cardoso, Mr Campelo said he was standing down because of what he described as the country's grave political situation.

The government says a new federal police chief will be named on Monday.

Mr Campelo resigned just a day after giving testimony to the Brazilian congress

Ever since his appointment was announced last week, Mr Campelo had become a severe embarrassment to the Brazilian government.

Like many other members of the security forces, Mr Campelo began his career during the country's long period of military rule between 1964 and 1985.

Brazil's military were less brutal than their counterparts in Chile and Argentina but serious abuses were committed, and it seems that no-one in the government bothered to check exactly what Mr Campelo's role had been.

Priest speaks out

As soon as his name was announced, a former priest, Jose Antonio Monteiro, alleged that he had been tortured at Mr Campelo's hands nearly 30 years ago in the north-eastern state of Maranhao.

The police chief denied the allegations, saying that Mr Monteiro was harbouring resentments from the time when they had both studied at the same seminary.

But when the two men appeared before Congress's human rights commission earlier this week, even pro-government legislators said they found the former priest more convincing than the police chief.

President Cardoso was reluctant to dismiss the man he had just appointed before the allegations against him could be conclusively proved.

But with pressure from all parties on him to resign it was only a matter of time before Mr Campelo took the inevitable decision.

Running the federal police is an important job since it involves control of Brazil's borders and of the fight against drug trafficking.