South Korea has warned businesses against inadvertently hiring IT workers from North Korea with fake identities who are using the money they earn to support their country's nuclear and missile programs.

In an advisory issued by the Foreign Ministry and the National Intelligence Service on Thursday, South Korea said North Korea dispatches thousands of IT workers around the world. Living in groups, the engineers are hired by companies to develop software and mobile applications.

The advisory says many of these North Korean workers pretend to be from other nations, using illegally obtained driving licenses and other IDs that have been forged with computer graphic software.

The advisory says North Korean IT workers earn hundreds of millions of dollars a year, and most of the money goes to a North Korean agency and helps to pay for the country's nuclear and missile development.

The South Korean government is calling on South Korean businesses to conduct thorough background checks of IT workers before giving them contracts.

The US government issued a similar warning about North Korean IT workers in May this year.

The US and South Korea warn that these IT workers are playing a major role in raising funds for Pyongyang's nuclear and ballistic missile programs at a time when UN sanctions are severely restricting North Korea's ability to earn foreign currency.