China's Commerce Ministry said on its website that all imports of coal, iron, iron ore, lead concentrates, lead and seafood from North Korea would be "completely prohibited" from Tuesday.

The announcement came after Beijing pledged to fully enforce the latest round of sanctions against its neighbor. US President Donald Trump has accused China of not doing enough - as the North's most important trading partner and ally - to pressure Pyongyang to abandon its nuclear weapons program.

But Chinese Foreign Minister Wang Yi had vowed after the UN sanctions were given the green light that his country "will for sure implement that new resolution 100 percent, fully and strictly."

The sanctions, approved in a Security Council vote on August 6, could cost North Korea up to $1 billion (850 million euros) a year.

Missiles and mounting tension

The UN resolution came after Kim Jong-un's regime carried out two intercontinental ballistic missile tests last month. Experts warn the rogue state may now be close to achieving its goal of striking the United States mainland with a nuclear weapon.

Read more: What is an intercontinental ballistic missile?

Escalating tensions between the US and North Korea, including threats of military action by both countries, have also led to mounting international concern.

Pyongyang says it is developing plans to strike the US territory of Guam, while Trump warned the North would face "fire and fury" if it attacked the United States.

Read moreDonald Trump has complete, unchecked authority to use nuclear weapons:

Meanwhile, US Joint Chief of Staff Chairman Joseph Dunford told his South Korean counterparts during a visit to the country on Monday that the US was willing to use the "full range" of its military capabilities to defend itself and its allies from North Korea if economic sanctions failed.

Chinese President Xi Jinping urged calm on both sides in a phone call with Trump over the weekend. South Korean President Moon Jae-In also appealed for restraint, calling for an end to "all provocations and hostile rhetoric immediately, instead of worsening the situation any further."

China maintains that it prefers diplomacy and a return to dialogue, rather than sanctions, as a way to resolve tensions with North Korea. Six-party talks involving China, the two Koreas, Russia, Japan and the United States collapsed in 2008.

nm/kms (Reuters, AFP)