A Chinese Triad gang may have used the postal system to launder and transfer up to £1m in drugs money, the High Court heard today.
Prosecutors revealed the alleged operation involved packages being sent between London and addresses in Belfast.
Counterfeit Chinese passports and nearly £70,000 in cash were seized during searches at one property in the east of the city last month.
Some of the money had been stuffed into hardback books with the insides removed.
Details emerged as bail was refused to a man claimed to be a highly-trusted member of the organised crime gang behind the racket.
Wen Zyang, 23, of no fixed address, is charged with possessing criminal property and false identity documents.
He also faces two counts of transferring criminal property, namely £60,000 and £30,000 in cash.
All of the alleged offences occurred between December last year and March.
The court heard how CCTV footage of a Chinese man paying rent on one of the suspected postal drop properties forms part of the police investigation.
Officers then searched a house off the Albertbridge Road and discovered two large parcels posted from London.
After setting out the suspected Triad involvement, a prosecution barrister said Zyang was present and told police: "It's only books."
One of the packages was opened and found to contain a large number of literature, magazines and an envelope with three counterfeit passports.
Around £28,000 in cash was discovered inside two hardback books, while nearly £40,000 more was located in a bedroom.
A judge was told that a 2013 diary with entries in Mandarian was also recovered and translated.
The barrister said police believe it contained references to drug-dealing and money laundering activity.
"A number of individuals are named purchasing and large sums of cash transferred through the postal system," she said.
"Police believe that approximately £1 million from this diary has been paid."
The court heard that Zyang made a number of admissions during questioning.
But opposing his release based on what police suspect, the prosecution lawyer claimed: "He's a highly-trusted member of this organised gang trusted with large sums of money."
Defence counsel Matthew Corkey said his client, who came to Northern Ireland last year, had confirmed his identity on CCTV footage and cooperated with police.
He stressed that none of the passports contained Zyang's photo.
"It does appear that this is going to involve a number of other individuals and other jurisdictions being investigated by other forces," Mr Corkey added.
But Mr Justice Treacy refused bail due to concerns the accused may flee or commit crime.
He said: "Given the organised and apparently Triad nature of the charges and the sheer scale of the illegality that there is in this case, there is a high risk of further offending."