Thai police seized fake US bonds worth $24.7 billion from a Bangkok bank vault today.
Police said the fake bonds were part of an elaborate scam in which fraudsters tried to pass them off as part of a World War Two treasure haul said to have been found in a remote cave.
The arrests were the latest chapter in a multi-billion-dollar attempted fraud which has caused a sensation in Thailand and badly dented the government's credibility.
Deputy National Police Chief Sant Sarutanond told a news conference police arrested the four suspects after they tried to sell the fake bonds to a brother of Prime Minister Mr Thaksin Shinawatra.
Police said two Filipinos, one Singaporean and a Thai citizen had been arrested on charges of trying to sell counterfeit debt papers.
The charges carry a maximum penalty of life in jail.