Foreign journalists visiting North Korea gathered in Pyongyang for "a big and important event" on Thursday with tensions high over the possibility of a new weapons test by the isolated state and as a US carrier group sails towards the Korean peninsula.

North Korea marks the 105th anniversary of the birth of the state founder Kim Il-sung on Saturday and in 2012 launched a long-range rocket carrying a satellite to mark the date. It tested a newly developed intermediate-range missile last year.

Around 200 journalists were invited to witness the nation's most important national holiday, known as the "Day of the Sun". They have been given no further details of the "big" event, although it coincides with a US naval strike group approaching the Korean peninsula and reports that the North's nuclear test site is "primed and ready" for a new underground detonation.