South Korea has reported that North Korea fired seven suspected artillery shells into the ocean on Tuesday, in what Seoul called a provocation apparently directed against its ongoing military drills with the US.

North Korea has already launched six Scud missiles into the sea since the annual exercises began about a week ago. Pynongyang has claimed the exercises are a rehearsal for invasion, but Washington and Seoul say they are defensive in nature.

Despite the firings and launches, analysts outside the North say the regime is taking a softer stance toward the drills this year than last year because it hopes to forge better ties with the outside world and revive its struggling economy.

Three of the projectiles fired had a range of 30 miles and four could travel about 95 miles, according to Seoul's defence ministry. Spokesman Kim Min-seok said the various launches were apparently an "armed protest" against the drills.