DAP lawmaker Tony Pua wants to know whether Bank Negara has investigated the US$1billion that was allegedly deposited into Prime Minister Najib Razak's personal bank accounts for possible money-laundering offence.

Pua posed this question in the wake of the actions of Switzerland's Office of the Attorney-General (OAG) and Monetary Authority of Singapore (MAS) in shutting down BSI Bank branch in the island nation.

"What has Bank Negara done to protect the integrity of our financial system?" he asked at a press conference at the Parliament lobby today.