South Korean authorities have reportedly seized Bithumb, one of the country’s biggest cryptocurrency exchanges by trading volume.

The Seoul Newspaper reported Wednesday that officers from the Seoul Metropolitan Police Agency's Intelligent Crime Investigation Unit had raided Bithumb's headquarters, located in the capital's central Gangnam District.

The police action was apparently linked to a $25 million token sale hosted on Bithumb and a proposed acquisition by a Singapore platform, BTHMB, that never materialized.

Per a report from TheNews, some investors said they lost millions participating in the sale.

Bithumb's chairman, Lee Jung-hoon has been accused of fraud and illicitly sending funds overseas.

CoinDesk has approached Bithumb for confirmation.

This is the second raid on a Korean cryptocurrency exchange in a week.

Last week, police seized Coinbit – the country's third-largest exchange – on allegations it had faked most of its trading volumes.

Bithumb is one of Korea's largest cryptocurrency exchanges – 24h trading volume stood at over $365 million, according to CoinGecko.

The exchange appeared to still be active at press time.