Tensions on the Korean peninsula festered on Friday as North Korea held its largest-ever military drills and prepared to bring about "the most miserable doom to the U.S. imperialists and the South Korean puppet group of traitors."

The drills were said to be part of a "simulated attack" on the Blue House, the official residence of South Korean president Park Geun-Hye.

They are also believed to be a furious reaction to mass military demonstrations held by South Korea and the US earlier in March, which regime leader Kim Jong-un perceives as a rehearsal for invasion.

Newly released images by North Korea's state broadcaster show its Supreme Commander - who appears to have put on substantial amounts of weight since he came to power - inspecting soldiers at a massive military parade.