At least 75 inmates, including members of Brazil's most powerful gang, have escaped from a Paraguayan prison after digging a tunnel in an operation suspected to involve prison staff, the Government says.

Key points: Escapees included members of Brazil's First Capital Command (PCC) criminal gang

Escapees included members of Brazil's First Capital Command (PCC) criminal gang The director of the prison, along with six other staff, have been fired

The director of the prison, along with six other staff, have been fired It is believed the prisoners are still within Paraguayan territory

Officials said they discovered a tunnel in the prison in the city of Pedro Juan Caballero, near the Brazilian border, and found cells filled with as many as 200 bags of earth.

"It's not possible that nobody saw anything in all this time," Justice Minister Cecilia Pérez told the Telefuturo station.

"This isn't the work of one day or one night."

Pedro Juan Caballero is considered a transit point for drug trafficking and other criminal activity. ( ABC News: Alan Weedon )

Ms Pérez also confirmed that the director of the prison was fired along with six other prison officials.

Interior Minister Euclides Acevedo said in a statement that the tunnel itself may have been a ruse to cover complicity by prison officials and that many of the inmates may have been allowed to walk out of the prison's main gate.

Mr Acevedo said the majority of the escapees belong to the First Capital Command based in Brazil, which borders the city of Pedro Juan Caballero, where the prison is located.

The gang was founded in the 1990s inside a Sao Paulo prison and it has extended its influence throughout the country, becoming one of Brazil's largest criminal organisations.

The Paraguayan Interior Minister said the tunnel and its debris might have been an elaborate ruse. ( Twitter: Iván Leguizamón )

In Brazil, Justice Minister Sergio Moro said authorities were trying to prevent the escapees from re-entering the country.

"If they enter Brazil again, they will only get a one-way ticket to federal prison," he tweeted.

Brazilian authorities said 40 of the escapees were Brazilian, and said they had passed their names and photos to border police.

The border region near Pedro Juan Caballero is considered a transit point for drug-trafficking and other criminal activity by gangs like Brazil's PCC and Comando Vermelho, or Red Command.

"In that area there are many woods and they know the territory… these are highly dangerous people," Paraguayan Attorney General Sandra Quinonez told the country's Radio Monumental.

Paraguayan authorities believe prison chiefs were aware of the escape plan. ( AP: Marciano Candia )

Reuters