North Korea used civilian passenger planes to transport hard currency seized from expat laborers in the Middle East following the closure of its overseas banks for violating international law.

Sources said since prosecutors in Kuwait ordered the closure of the local branch of North Korea's Trade Bank on charges of money laundering and illicit transfers, the North has used twice-monthly Air Koryo flights to Kuwait to ferry seized wages back to the North.

There are 50,000 to 60,000 North Korean laborers in 16 countries. In Kuwait, there have been some 4,000 since 1995, toiling at construction sites and receiving around W1 million a month (US$1=W1,123), of which the regime confiscates 70 to 80 percent.

The workers send the remainder back to their families in the North and often survive by begging or taking on overtime and extra menial jobs.

Around 2,000 North Koreans work in the United Arab Emirates and 1,800 in Qatar.