North Korea appears to be preparing for future rocket tests by developing a second submersible barge from which to launch ballistic missiles, according to new satellite imagery.

Its other test barge, which was obtained in 2014 and based at Sinpo South Shipyard, has been used to support the development of strategic submarine-launched ballistic missiles (SLBMs) and North Korea’s largest experimental ballistic missile submarine.

Satellite imagery shows the new barge has been moved to a fitting-out dock at the shipyard since previous images taken in December.

North Korea announces intercontinental missile launch Show all 13 1 /13 North Korea announces intercontinental missile launch North Korea announces intercontinental missile launch Pyongyang residents react after the news of the successful launch of the new intercontinental ballistic missile AFP/Getty Images North Korea announces intercontinental missile launch North Korea's leader Kim Jong Un signing an order to test-fire the newly developed inter-continental ballistic missile KRT via AP Video North Korea announces intercontinental missile launch A news broadcast displays Kim Jong Un's signed document AP North Korea announces intercontinental missile launch People cheer as they watch the news broadcast announcing Kim Jong Un's order to test-fire the new inter-continental ballistic missile AFP/Getty Images North Korea announces intercontinental missile launch Residents react after the document signing AP North Korea announces intercontinental missile launch Pyongyang residents celebrate Kim Jong Un's announcement AFP/Getty North Korea announces intercontinental missile launch Cheering Pyongyang residents react AP North Korea announces intercontinental missile launch To counter North Korea's missile test, South Korea fired missiles into the East Sea The Defence Ministry/Yonhap via REUTERS North Korea announces intercontinental missile launch The Hyunmu-2 missiles firing during the drill South Korean Defense Ministry vi North Korea announces intercontinental missile launch The exercise was carried out in an attempt to counter Kim Jong Un's order South Korea Defense Ministry via AP North Korea announces intercontinental missile launch The South Korean army continue to carry out military exercises AP North Korea announces intercontinental missile launch Where K-9 self-propelled howitzers were taking part in a drill Rex Features North Korea announces intercontinental missile launch US soldiers are also present in the border city of Paju AFP/Getty Images

The dock is typically where vessels are moved to when their hulls are sound yet they require systems, such as pumps, electrics and communications, to be installed, the North Korea analysis website 38 North reported.

There is also a small floating crane moored alongside the barge, with its boom extended over the vessel.

The purpose of the work is unclear. It probably concerns final stages of repair before the barge is declared operational, Joseph S Bermudez Jr, an analyst at 38 North said.

He said it was unclear when the barge would become operational.

North Korean delegation to go to Winter Olympics in South Korea

Kim Jong-un, the leader of the totalitarian state, has refused to give up the goal of developing nuclear missiles capable of hitting the US despite increasingly severe international sanctions.

At the same time, North and South Korea have come to something of a rapprochement with a number of collaborative projects around this year's Winter Olympics in South Korea.

Critics warn the North’s overture is an attempt to use improved ties with the South to weaken US-led international sanctions as it stalls for time to perfect is nuclear weapons programme.