North Koreans prepare to celebrate the 'Day of the Sun' as tension mounts preemptive strike before 'nuclear bomb test'

North Koreans are set to celebrate the "Day of the Sun" festival amid concerns that it will coincide with a sixth nuclear test or more missile launches.

Saturday's festival commemorates the 105th birthday anniversary of former supreme leader Kim Il-sung, the country's founder and grandfather of current leader Kim Jong-un.

Major holidays are usually celebrated with a test of the secretive state's nuclear or missile capabilities, and a launch this weekend would come at a time when tensions between North Korea and the West are at their highest in years.

Vice Minister Han Song Ryol said in an interview on Friday that North Korea would conduct another nuclear test whenever it sees fit.

On the eve of the festival China has warned that “conflict could break out at any moment” in the Korean peninsula.

The US is prepared to launch a preemptive strike against North Korea should officials become convinced that Jong-un will follow through with his threat of a nuclear weapons test in defiance of UN sanctions.

US Vice President Mike Pence is set to arrive in South Korea on Sunday as part of a 10-day visit to Asia.

North Korea denounced the US on Friday for bringing "huge nuclear strategic assets" to the peninsula as the USS Carl Vinson strike group headed to the region in a show of force.

North Korea had already warned that it was "ready for war" and would defend itself should the US launch a preemptive strike in response to the strike group being diverted to the region and America's air strike on a Syrian air base.

Meanwhile, photos from Pyongyang showed North Koreans preparing for Saturday's massive celebration.

It is the state's most important public holiday and will be marked with commemorations at Kumsusan Palace of the Sun, where Il-sung's body is kept, and at statues around the country.

Missiles are displayed during massive military parades, while other festivities include dance and athletic performances and fireworks.

Civilians are said to be given more food rations during the three-day holiday, which begins with the festival and is followed by two days of rest.

Soldiers visited Il-sung's birthplace on Friday to pay tribute to the founder, with the state news agency reporting that "an endless stream" of military personnel, citizens and schoolchildren visited a memorial site in Mangyongdae.

Fears of a new conflict on the peninsula have sparked concerns about a possible humanitarian crisis.

Japan has discussed how to evacuate nearly 60,000 of its citizens from South Korea in the event of a crisis and how to cope with a possible flood of North Korean refugees.

China has reportedly moved 150,000 troops and medical supplies to its border with North Korea in case there is a refugee crisis.

China's Foreign Minister Wang Yi said on Friday that is was necessary to prevent the situation on the Korean peninsula from going down an irreversible route.