China announced Saturday that it was suspending coal imports from North Korea for three weeks, in line with the latest United Nations sanctions against the hermit state.

"After the adoption of UN Security Council resolution 2321... China is suspending North Korean coal imports," the government said in a statement.

The three-week suspension starts Sunday and ends on December 31, according to the statement.

The Security Council passed the resolution on the international sanctions against Pyongyang on November 30 in the wake of the North's September 9 nuclear test.

It limits North Korea's coal exports next year to 7.5 million tonnes or just over $400 million, down 62 percent on 2015.

The cap represents a fraction of the North's current annual exports to China, the isolated country's sole ally and its main provider of trade and aid.

China imported 1.8 million tonnes of coal worth $101 million from North Korea in October alone, according to the most recent figures available on the Chinese Customs website. The volume was up nearly 40 percent year-on-year.

Under previous sanctions, the Security Council authorised the purchase of coal from North Korea provided revenues were not used to finance Pyongyang's nuclear programme.

However, the UN did not specify any assessment criteria, which allowed Beijing to increase its imports considerably while saying it was acting in good faith.

Between March and October, 24.8 million tonnes of coal was imported, three times the annual limit now allowed by the UN.

Although Beijing has traditionally protected Pyongyang diplomatically, believing that Kim Jong-Un's regime is preferable to its collapse, it has grown frustrated by its neighbour's defiance.