North Korea has unveiled a new type of submarine-launched ballistic missile, described by state media as "the world's most powerful weapon".

Several of the missiles were displayed at a parade overseen by leader Kim Jong-un, reported state media.

The show of military strength comes days before the inauguration of Joe Biden as US president.

It also follows a rare political meeting where Mr Kim decried the US as his country's "biggest enemy".

Images released by North Korean state media showed at least four large black-and-white missiles being driven past flag-waving crowds.

Analysts noted it was a previously unseen weapon. "New year, new Pukguksong," tweeted North Korea expert Ankit Panda, using the North Korean name for their submarine-launched ballistic missiles (SLBMs).

Clad in a leather coat and fur hat, Mr Kim is pictured smiling and waving as he watched the display in Pyongyang's Kim Il Sung Square, which also included infantry troops, artillery and tanks.

"The world's most powerful weapon, submarine-launch ballistic missile, entered the square one after another, powerfully demonstrating the might of the revolutionary armed forces," the official Korean Central News Agency said.

The event on Thursday did not showcase North Korea's largest intercontinental ballistic missile (ICBM), which was unveiled at a much larger military parade in October. That colossal weapon is believed to be able to deliver a nuclear warhead to anywhere in the US, and its size had surprised even seasoned analysts when it was put on show last year.

The country's latest display of its arsenal comes at the end of a five-yearly congress of the ruling Workers' Party.

In his address to members last week, Mr Kim had pledged to expand North Korea's nuclear weapons and military potential, outlining a list of desired weapons including long-range ballistic missiles capable of being launched from land or sea and "super-large warheads".

He also said that the US was Pyongyang's "biggest obstacle for our revolution and our biggest enemy... no matter who is in power, the true nature of its policy against North Korea will never change".

Under Mr Kim's leadership North Korea has made rapid progress in its weapons programme, which it says is necessary to defend itself against a possible US invasion.

The unveiling of the new missiles appears designed to send the incoming Biden administration a message of the North's growing military prowess, say experts.

"They'd like us to notice that they're getting more proficient with larger solid rocket boosters," Mr Panda tweeted, noting what appeared to be new solid-fuel short-range ballistic missiles on display too. These missiles can be launched more quickly than liquid-fuelled varieties.

Over the last four years, Pyongyang has had an erratic relationship with the US under President Donald Trump's administration. Mr Kim and Mr Trump engaged in mutual insults and threats of war before an unprecedented summit in Singapore in 2018 and declarations of love by the outgoing US leader.

Despite the apparent warming of relations, little concrete progress was made on negotiations over North Korea's nuclear programme and a second summit in Hanoi in 2019 broke down after the US refused Pyongyang's demands for sanctions relief.