BRASILIA (Reuters) - The top prosecutors of Brazil and Argentina are accusing their governments of interfering in the creation of a joint anti-corruption task force to investigate bribes by the Odebrecht engineering group so that politicians, many of whom are under investigation, can themselves control the exchange of evidence.

Brazil's Prosecutor General Rodrigo Janot said on Tuesday the two countries had agreed in June to set up a task force to allow the rapid and simultaneous investigation of bribes paid by Odebrecht, but the joint effort has not taken off.

"The task force is an essential tool without which we cannot join forces regionally to fight corruption," he told reporters.

A statement issued late on Monday by Janot and his Argentine counterpart, Alejandra Gils Carbo, accused the governments of their countries of interfering in the effort to jointly investigate the Odebrecht bribe network.

"The main authorities for international legal cooperation -- Brazil's Justice Ministry and Argentina's Foreign Ministry -- have placed obstacles and made requisitions that are an undue interference in carrying out agreements signed by prosecutors of the two countries in the Odebrecht investigation," the statement said.

"We hope the central governments support our efforts and urgently remove the obstacles that have been imposed," it said.

They said Brazil's Justice Ministry has sought to establish the rules of the joint force so evidence was shared through government channels and not directly between the prosecutors.

In Argentina, they said, the Foreign Ministry wanted to turn the task force into a treaty signed by the government, undermining cooperation between the actual investigators.

Odebrecht, Latin America's largest construction firm, is at the centre of a global graft scandal. As part of a $3.5 billion settlement with Brazilian, U.S. and Swiss authorities in December, the company admitted to paying bribes in 12 mostly Latin American countries, including $35 million in Argentina, to secure lucrative contracts. Prosecutors in Argentina are also investigating four projects involving Odebrecht, the largest construction firm in Latin America, for corruption.

U.S. prosecutors said Odebrecht paid approximately $788 million in bribes in association with 100 projects in 12 countries between 2001 to 2016, through carefully disguised payments routed through a network of shell companies.

Janot said it was not the first time prosecutors have run into hurdles in setting up binational task forces to investigate international connections of Brazil's massive graft scandal first centred on contracts at state-run oil company Petrobras.

A task force proposed by Swiss prosecutors a year ago and another sought six months ago by Spanish prosecutors never got off the ground. "And now this one with Argentina," Janot said.

(Reporting by Anthony Boadle; Editing by Alistair Bell)