A Russian politician says he has seen a North Korean missile that could reach the US west coast, and that Pyongyang plans on testing a long-rage missile "in the nearest future".

Anton Morozov told Russian state-backed news agency RIA Novost that he and two colleagues had visited North Korea, where they were shown the North Korean calculations that the missile could hit America. During the visit, earlier this week, officials told them they had developed technologies that would allow their missiles to withstand the heat while entering the atmosphere after a launch.

The North Koreans showed him the "mathematical calculations which they say prove that their missile is capable of reaching the US west coast," he said.

Mr Morozov's party, the Liberal Democratic Party of Russia, has a right-wing, nationalist agenda and is know for its anti-American sentiments. He did not indicate that he and his colleagues had personally reviewed the North Korean calculations to confirm their veracity.

North Korea has tested its missiles on at least 14 different occasions this year alone, leading to heightened tension between Donald Trump and North Korean leader Kim Jong-un. The North Korean regime has, at the same time, openly flouted its burgeoning nuclear capabilities, and conducted its sixth nuclear test ever last month. Meanwhile, intelligence leaks have indicated that North Korea is capable of producing a nuclear warhead small enough to be attached to one of those intercontinental ballistic missiles (ICBMs).

At the same time, Donald Trump and North Korean officials have engaged in a war of insults. The President said that Mr Kim is on a "suicide mission for himself and his regime" during his first speech to the United Nations General Assembly last month, and said that he was ready to use military force against the country if necessary. In response, Mr Kim released an unprecedented personal response, calling Mr Trump a "dotard" and a "frightened dog."

Kim Jong-un inspects weapon North Korea says is powerful hydrogen bomb Show all 6 1 /6 Kim Jong-un inspects weapon North Korea says is powerful hydrogen bomb Kim Jong-un inspects weapon North Korea says is powerful hydrogen bomb Photos released by North Korea show Kim Jong-un talking to subordinates next to a device thought to be the new thermonuclear weapon. There is no way of independently verifying the pictures STR/AFP/Getty Images Kim Jong-un inspects weapon North Korea says is powerful hydrogen bomb North Korea claims it has successfully tested an advanced hydrogen bomb which could be loaded onto an intercontinental ballistic missile AFP/Getty Kim Jong-un inspects weapon North Korea says is powerful hydrogen bomb A diagram on the wall behind Mr Kim shows a bomb mounted inside a cone STR/AFP/Getty Images Kim Jong-un inspects weapon North Korea says is powerful hydrogen bomb North Korean leader Kim Jong-Un (C) attending a photo session with participants of the fourth conference of active secretaries of primary organisations of the youth league of the Korean People's Army (KPA) in Pyongyang STR/AFP/Getty Images Kim Jong-un inspects weapon North Korea says is powerful hydrogen bomb A new stamp issued in commemoration of the successful second test launch of the "Hwasong-14" intercontinental ballistic missile KCNA via Reuters Kim Jong-un inspects weapon North Korea says is powerful hydrogen bomb A new stamp issued in commemoration of the successful second test launch of the "Hwasong-14" intercontinental ballistic missile KCNA via Reuters