North Korea could be planning its first nuclear weapon test in nearly five years, according to a senior US official who urged the regime to step back from further provocations following its recent long-range missile test.

Sung Kim, the special representative for North Korea policy at the US state department, said Washington believes Pyongyang could demonstrate its growing nuclear weapons capacity on 15 April, an annual holiday held to celebrate the 110th anniversary of the birth of the country’s founder, Kim Il-sung.

“We are worried that in connection with the upcoming anniversary, the DPRK may be tempted to take another provocative action,” Kim told reporters on Wednesday, using the country’s official name, the Democratic People’s Republic of Korea.

He added: “I don’t want to speculate too much, but I think it could be another missile launch, it could be a nuclear test.

“Hopefully, the anniversary can pass without any further escalation.”

North Korea has conducted six nuclear tests since 2006, four of them under the current leader, Kim Jong-un. Its last test, in 2017, was followed by a self-imposed moratorium as Kim prepared for his first denuclearisation summit with Donald Trump the following year.

The Biden administration has called for a resumption of talks “without preconditions” but has made clear that the aim would be the removal of North Korea’s nuclear deterrent, a concession few analysts believe Kim Jong-un is willing to make as long as he believes the US is a threat to his regime..

The North has continued to ignore Washington’s offers to resume discussions on removing all nuclear weapons from the Korean peninsula, Sung Kim said.

“We have not received any response from Pyongyang, which is very disappointing, because we have sent several messages, both public and private, inviting them to a dialogue without any conditions,” he said.

“Instead they have initiated a series of missile tests that recently culminated in at least three ICBM launches. These actions pose a serious threat to regional stability.”

He added: “The DPRK finds itself isolated in unprecedented ways. It has shut itself off during the Covid pandemic. Only the resumption of diplomacy can break this isolation, and only then can we pick up the important work that has been done before.”

Sung Kim said China – the North’s main ally and biggest trading partner – and Russia were not helping Joe Biden’s push to restart talks with the North Korean leader.

Negotiations aimed at containing Pyongyang’s nuclear threat appeared to make progress under Trump, but then halted after he and Kim failed to agree on sanctions relief in return for verifiable moves to dismantle the North’s nuclear arsenal.

US and South Korean officials have said Pyongyang appears to be repairing underground tunnels at the Punggye-ri nuclear test site, which it had purportedly demolished in 2018 to show its willingness to denuclearise.

After Biden took office, North Korea began a series of missile tests – 13 in all – that culminated last month in the launch of a ballistic missile that could theoretically deliver a nuclear warhead to the US mainland.

On Tuesday, Kim Jong-un’s powerful sister Kim Yo-jong warned that Pyongyang will use its nuclear weapons to “eliminate” South Korea’s army in the event they launch a preemptive strike.

Sung Kim said that Washington was pushing for a fresh resolution condemning Pyongyang’s actions at the UN security council.

But he noted that in six earlier efforts this year, Russia and China “have consistently blocked our efforts to produce a UN public statement”.

He said: “We believe that the unprecedented number of DPRK ballistic missile launches this year and the instability they bring to the Korean peninsula are obviously in nobody’s interest, and we call on [China], as well as Russia, to work with us to send a very clear message through the security council that North Korea’s actions are unacceptable.”