LIMA (Reuters) - A scandal involving bribes Brazil's Odebrecht distributed in Peru during three presidencies is shaping up to be bigger than the massive graft case that toppled former leader Alberto Fujimori, the country's attorney general said on Wednesday.


Asking for patience from Peruvians eager to know the names of officials who took $29 million in bribes from Odebrecht, Pablo Sanchez said prosecutors were working hard to capture any "big fish" involved.,


"This is a very big case, I dare to say it's even bigger than the one we dealt with before," Attorney General Pablo Sanchez told reporters in reference to graft in Fujimori's government.


Fujimori fled Peru for Japan in 2000 as prosecutors probed years of corrupt deals that his spy chief Vladimir Montesinos had hashed out with judges, lawmakers and businessmen. Fujimori was eventually extradited to Peru where he has received several sentences for corruption and human rights abuses.


Jose Ugaz, the special attorney who led the inquiry and the current head of anti-graft group Transparency International, has described the extent of graft in Fujimori's government as unique because it had captured entire institutions.


Odebrecht's acknowledgement of having bribed unnamed high ranking Peruvian officials between about 2005 and 2014 has raised questions about whether Peru's three presidents after Fujimori were also corrupt - prompting calls from some to arrest them before they can flee.

Former Presidents Alan Garcia and Alejandro Toledo have denied any involvement in Odebrecht's kickback schemes.

Ollanta Humala has previously denied taking bribes from Odebrecht but has not made any public comments since the scandal broke in December.

Sanchez said prosecutors were evaluating opening a formal inquiry into Humala in the Odebrecht case. Humala is already a suspect in a money laundering inquiry that involves Odebrecht and has been barred from leaving the country without permission from a judge.

In the past week, authorities in Peru have arrested two former officials in Garcia's government accused of taking bribes from Odebrecht, but a third suspect had already left the country.

"It's not an easy investigation," Sanchez said. "Certainly a lot of people want it to fail...we're getting information bit by bit."

Odebrecht told Reuters Tuesday that it expects to reach a plea deal with Peru in two to four weeks.

(Reporting By Mitra Taj; Editing by Andrew Hay)