Pyongyang has sent thousands of troops to reinforce Russia's war effort, including to the Kursk border region, where both Ukraine and the United States say North Korean forces have suffered casualties.

"Direct DPRK support for Russia's war of aggression against Ukraine marks a dangerous expansion of the conflict, with serious consequences for European and Indo-Pacific security," the statement said, referring to North Korea by an abbreviation for its official name.

The foreign ministers of Australia, Canada, France, Germany, Italy, Japan, South Korea, New Zealand, the United Kingdom, the United States and the high representative of the European Union signed the release.

They also said that they were "deeply concerned about any political, military, or economic support that Russia may be providing to the DPRK's illegal weapons programs, including weapons of mass destruction."

On Monday, the US Treasury Department unveiled sanctions on nine people and seven entities over their provision of financial and military support to North Korea, including the Golden Triangle Bank and Korea Mandal Credit Bank.

Among those targeted for providing military support was Ri Chang Ho, a general said to be accompanying North Korean troops deployed to Russia.

The US State Department also imposed sanctions on three parties with ties to North Korea's ballistic missile program.

"These actions reflect the DPRK's escalating provocation and hostile military posturing that exacerbate global tensions and destabilize regional peace and security," said the US Treasury Department.

- Casualties in Kursk -

North Korea and Russia have strengthened their military ties since Moscow's invasion of Ukraine in February 2022. A landmark defense pact between Pyongyang and Moscow signed in June came into force earlier this month.

Experts say the nuclear-armed North's leader, Kim Jong Un, is keen to acquire advanced technology from Russia and battle experience for his troops.

Signatories of Monday's joint statement said they "condemn in the strongest possible terms the increasing military cooperation," including the "deployment of DPRK troops to Russia for use on the battlefield against Ukraine."

They added that the export of ballistic missiles, artillery shells and other military materiel by Pyongyang to Russia as well as Moscow's training of North Korean soldiers involving arms "represent flagrant violations of United Nations Security Council resolutions."

"We urge the DPRK to cease immediately all assistance for Russia's war of aggression against Ukraine, including by withdrawing its troops," the statement said.

The United States and South Korea have accused the North of sending more than 10,000 soldiers, and the Pentagon said Monday that Pyongyang's forces have entered combat in Kursk alongside Russian forces, suffering casualties.

"We do have indications that they have suffered casualties... both killed and wounded," Pentagon spokesman Major General Pat Ryder told journalists.

Ukraine meanwhile said Monday that its troops killed or wounded at least 30 North Korean soldiers in Kursk over the weekend.