By Joshua Franklin and Saeed Azhar
ZURICH/SINGAPORE (Reuters) - Swiss prosecutors are investigating whether the country's banks were used to misappropriate $800 million (628.8 million pounds) belonging to a former subsidiary of Malaysian state investment fund 1MDB.
Switzerland's Office of the Attorney General (OAG) said on Wednesday a Ponzi scheme may have been set up to conceal the alleged fraud, adding it was seeking further help from Malaysia for its investigation.
It is the latest development in a number of investigations around the world related to allegations of the misappropriation of funds and money-laundering surrounding 1Malaysia Development Berhad, commonly known as 1MDB.
Founded by Prime Minister Najib Razak, who chaired its advisory board, 1MDB is currently the subject of money-laundering investigations in at least six countries including Switzerland, Singapore and the United States.
Najib has denied any wrongdoing and said Malaysia will cooperate with the international investigations.
Speaking in Singapore, Swiss Attorney General Michael Lauber said on Wednesday there was a "serious suspicion" that Swiss banks were involved in alleged criminal activities linked to 1MDB.
Lauber's office has been running an investigation around 1MDB for more than a year and has so far opened criminal proceedings against four people and one bank.
In a statement on Wednesday it said it had found new evidence of "suspect transactions involving the Swiss financial sector".
"Firstly, the sum of $800 million appears to have been misappropriated from investments in natural resources made by the SRC sovereign fund," the OAG said, referring to a former 1MDB subsidiary now owned by Malaysia's finance ministry.
"Secondly, it is suspected that a 'Ponzi' scheme fraud ... was committed to conceal the misappropriations from both the SRC fund and from 1MDB."
A Ponzi scheme involves paying the returns on initial investments from funds obtained from subsequent investors, rather than from legitimate revenue from the investments.
The aim of the latest Swiss OAG request for Malaysian legal assistance is to gather further evidence to support these findings, Lauber's office said, adding an initial request for assistance in January was still pending.
1MDB said in a statement any queries should be addressed to the relevant authority and that it had not been contacted by the OAG or any other foreign agency regarding their investigations but would cooperate fully with any of the authorities.
Malaysia's Attorney General's office did not immediately respond to requests for comment.
In May the OAG said it had opened criminal proceedings against Lugano, Switzerland-based BSI bank as part of its investigations surrounding 1MDB. BSI is in the process of being bought by EFG International (S:EFGN).
BSI did not directly comment on the proceedings at the time, but said that group CEO Stefano Coduri had stepped down with immediate effect and it had undertaken steps to strengthen management, including introducing a new chief risk officer and appointing a new group legal counsel.
Lauber's office also said in April it had extended its criminal investigation to two former Emirati officials, in charge of Abu Dhabi sovereign funds. It did not name the officials or the funds.