North Korea has warned Australia it is "suicidal" to conduct military drills with the United States after a handful of Australian troops began an annual war game with the US and South Korea on Monday.

Tens of thousands of military personnel are involved in the Ulchi Freedom Guardian drills, a 10-day exercise in South Korea that simulates war on the Korean Peninsula.

About 25 Australian troops join 17,500 from the US and 50,000 from South Korea, as well as a small number from Canada, Colombia, Denmark, New Zealand, the Netherlands and the United Kingdom.

On Saturday, a spokesman for North Korea's Ministry of Foreign Affairs told state news agency KCNA that Australia's participation is aggravating the situation in the region.