The story remains sketchy for the time being (it supposedly occured 3 years ago and is now just being investigated), but apparently a HSBC employee stole data on the bank’s high-value customers and was trying to sell the information to a Lebanese bank:

Banking giant HSBC has said that 15,000 Private Bank customers may have been affected by a data breach that occured approximately three years ago.

A former HSBC employee called Herve Falciani is under investigation in connection with the theft of the data, an HSBC spokesperson told ZDNet UK on Friday. The bank is not sure how the data was stolen, but said that it may have been transferred using a portable computer.

Falciani is alleged to have stolen the data during a project to transfer the information to a more secure system, said HSBC. He was caught at the beginning of 2008 trying to sell the data to different Lebanese banks, said the spokesperson.

Its not clear how he was caught though other media are reporting that he tried to sell it to one Lebanese bank and failing to do so, he fled to France.

More news on this story as it develops.

Stolen HSBC Client Data was Unsuccessful Sold to an unnamed Lebanese Bank