SEOUL, South Korea — A senior Chinese diplomat reportedly visited North Korea on Monday, the first high-ranking official to do so in eight months.

Vice Foreign Minister Liu Zhenmin led a Chinese delegation attending a meeting to discuss joint border issues, North Korea’s state-run Korean Central News Agency said.

China is facing pressure from the U.S. and its allies to do more to rein in the growing nuclear and missile threat from the North.

Washington is seeking Beijing’s help in pushing a set of toughened sanctions through the U.N. Security Council to punish North Korea for its fifth and largest nuclear test on Sept. 9. But the two countries have seen their relations strained over U.S. plans to deploy an advanced missile defense system in South Korea and disputes over the South China Sea.

South Korea’s Yonhap news agency reported that Liu was the first known high-ranking Chinese official to visit North Korea since February. China had no immediate comment on the reports.

China is North Korea’s main ally but has shown growing impatience over its protege’s defiance.

Beijing signed onto the most recent round of sanctions, which were imposed in March after Pyongyang conducted its fourth nuclear test and a long-range rocket launch. But the U.S. has pressed it to do more to implement the measures.

Liu’s trip would suggest the two countries are maintaining ties at least on routine matters.

It also came days after a North Korean delegation met with former U.S. government officials for informal discussions in Malaysia.

Yonhap reported that the U.S. delegation included Robert Gallucci, who negotiated a landmark 1994 nuclear freeze deal with Pyongyang, and Leon Sigal, director of the Northeast Asia Cooperative Security Project at the Social Science Research Council in New York.

The North’s deputy ambassador to the United Nations Jang Il Hun told Yonhap he traveled to Malaysia through Beijing, adding that the two sides talked about several “pending issues and each other’s thoughts on them.”

Tensions have risen as North Korea test-fired some two dozen ballistic missile tests this year. It tried to launch two intermediate-range Musudan missiles last week, but U.S. and South Korean officials said they both exploded shortly after takeoff.

The U.S. and South Korea agreed during high-level talks in Washington to boost military and diplomatic efforts against the North.

Secretary of State John Kerry also promised to deploy the anti-missile battery known as THAAD “as rapidly as possible,” and to press for tighter sanctions that close humanitarian loopholes the U.S. believes are being exploited.

A North Korean official denounced the sanctions and related U.N. resolutions in an interview with Associated Press Television Monday in Pyongyang.

“The sanction resolutions of the U.N. Security Council are illegal criminal documents,” said Pang Kwang Hyok, vice director of the department of international organizations at the North Korean Foreign Ministry.

Pang also reiterated the North’s insistence that it will continue developing its nuclear arsenal despite the international condemnation. “I can state that it is a complete miscalculation to think that any sanctions or pressure can have any effect on us,” he said.

gamel.kim@stripes.com Twitter: @kimgamel

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