The Philippines government says it may cancel a Japanese firm's US$2 billion casino complex project if it is found that the concession was obtained through bribery.

According to a report in The Philippine Daily Inquirer on Tuesday, Philippine authorities said the casino operating licence issued to Universal Entertainment Corp owned by Kazuo Okada, a Japanese billionaire, could be revoked if there is insurmountable evidence that corruption was involved.

"If there's proof that the licence was obtained through bribery, then there may be reason to consider cancelling the contract," said Edwin Lacierda, the spokesperson for President Benigno Aquino.

It has been alleged the company made a $5 million payment to Philippine Gaming Corp (Pagcor) in 2010.

Back then, Universal Entertainment was awarded a provisional licence when it invested $300 million for land where a casino complex would be built intended for wealthy Chinese tourists.

The government has pledged that due process will be observed in the investigation. 

Among 16 Pagcor officials facing charges is a former chairman Efraim Genuino.

Pagcor is seeking assistance from the Department of Justice and the National Bureau of Investigation in the probe.