SEOUL: The United States, South Korea and Japan expressed deep concern over North Korea’s “malicious” cyber activities to support its weapons programmes, in comments released in a joint statement on Friday.

Crypto currency funds stolen by North Korean hackers have been a key source for financing the sanctions-stricken country’s weapons programmes, officials and experts in the United States and its allies say.

A report released by the U.S. Treasury Department on April 6 said actors such as North Korea were using decentralised finance (DeFi), a thriving segment in the crypto sector, to transfer and launder their illicit proceeds.

North Korea has denied allegations of hacking or other cyberattacks.

Amid North Korea’s rising nuclear and missile threats, South Korea’s nuclear envoy held talks with his U.S. and Japanese counterparts in Seoul this week and condemned the isolated country’s weapons tests.

“We reiterate with concern that overseas DPRK IT workers continue using forged identities and nationalities” to evade U.N. sanctions and raise funds for missile programmes, according to the envoys’ joint statement, using the acronym for North Korea’s official name.

They called on United Nations member states to comply with U.N. Security Council resolutions to repatriate North Korean workers.

“We are also deeply concerned about how the DPRK supports these programmes by stealing and laundering funds as well as gathering information through malicious cyber activities,” the statement said.

Tensions on the Korean Peninsula are running high.

On Friday, North Korea was unresponsive to daily contact through a liaison phone line with South Korea, according to the South’s Unification Ministry which handles inter-Korean affairs.