SEOUL (Reuters) -North Korea "most strongly denounces" the declaration at the recent NATO summit, KCNA said on Saturday, citing the country's foreign ministry spokesperson.

Leaders of NATO countries stressed a membership pledge for Ukraine and took a stronger stance on China's support for Russia in a declaration this week at a summit in Washington.

"The "Washington Summit Declaration," cooked up and made public on July 10, goes to prove that the U.S. and NATO, reduced to a tool for its confrontation, pose the most serious threat to the global peace and security," North Korea's state media KCNA quoted a foreign ministry spokesperson as saying.

North Korea's statement added that the U.S. moves to expand military blocs with NATO countries and Asian partners, including South Korea and Japan are "the vicious root cause of seriously threatening the regional peace, extremely exacerbating the international security environment and sparking off worldwide arms race."

The summit declaration called on China to cease all material and political support for Russia's war effort. It also accused Iran and North Korea of fuelling Russia's war in Ukraine by providing direct military support to Moscow.

Separately, South Korea and the United States on the sidelines of a NATO summit signed a guideline on establishing an integrated system of extended deterrence for the Korean peninsula to counter nuclear and military threats from North Korea.

(Reporting by Heekyong Yang and Ju-min Park; Editing by Chris Reese and Sandra Maler)