UPDATE 1-Malaysia's top prosecutor studying possible criminal and civil action related to 1MDB probe

(Rewrites with details and background on 1MDB probe)

KUALA LUMPUR, June 12 (Reuters) - Malaysia’s attorney general on Tuesday said his office was studying possible criminal and civil action in the 1Malaysia Development Berhad (1MDB) case, after receiving investigation papers on the state fund from the anti-graft agency.

Malaysia reopened a probe into 1MDB following a stunning election victory last month by 92-year-old Mahathir Mohamad, who has vowed to bring back funds allegedly siphoned from 1MDB and punish those responsible.

Former prime minister Najib Razak, who founded 1MDB, is the subject of a money laundering probe. Najib has consistently denied wrongdoing. On Monday he said he did not benefit or steal money from 1MDB.

Najib has given statements to the Malaysian Anti-Corruption Commission (MACC) about a transfer of $10.6 million into his bank account from SRC International, a former unit of 1MDB.

The submission of the investigation papers by the MACC to the attorney general’s office indicates they may have completed their probe into SRC. It is now up to the country’s top prosecutor to decide if charges need to be filed or further investigations are needed.

“I have appointed a team to study the papers with a view to possibly instituting criminal prosecution, and another to study them with civil proceedings in mind,” Attorney General Tommy Thomas said in a statement.

The U.S. Department of Justice has alleged that more than $4.5 billion was misappropriated from 1MDB, and about $700 million of that went to Najib’s personal bank accounts.

Thomas also said he had signed mutual legal assistance requests from Switzerland, the United States, France and UAE regarding the 1MDB probe.

U.S. authorities saw Najib’s government as obstructing the investigation, sources told Reuters last week. Swiss Attorney General Michael Lauber said in April 2017 that Malaysian authorities have refused to cooperate.

Mohamed Apandi Ali, Malaysia’s previous attorney general, was ordered to go on leave by Mahathir, who has replaced several officials seen as close to Najib.

Earlier on Tuesday, Malaysia’s finance minister said the U.S. ambassador to Kuala Lumpur told him assets seized by the United States as part of its 1MDB probe will be monetised and returned to Malaysia.

Reporting by A. Ananthalakshmi; Editing by Michael Perry