North Korean dictator Kim Jong Un
North Korean dictator Kim Jong Un Reuters

The United Nations Security Council is set to vote on Wednesday to impose new sanctions on North Korea for its fifth and largest nuclear test, diplomats told Reuters on Monday.

The new measures will slash Pyongyang's export earnings by some $800 million.

Diplomats said the council's five veto-wielding powers - the United States, China, Britain, Russia and France - had agreed to new measures that largely target the isolated country’s coal export earnings.

"We didn't get everything we wanted," said a U.S. official familiar with the draft resolution, though he added the proposed new sanctions were "pretty good."

North Korea has been under UN sanctions since 2006 over its nuclear and missile tests. It has repeatedly conducted nuclear tests in violations of those sanctions, the last such test occurring September 9.

Since that time the United States and China, a North Korea ally, spent over two months negotiating new sanctions. The draft text was given to all 15 Security Council members on Friday, according to Reuters.

China is believed to be the only country that now buys North Korean coal and under the U.S.-drafted UN resolution likely to be adopted on Wednesday it would cut its imports by some 60 percent, or $700 million on 2015 sales, diplomats said.

The new sanctions would cap North Korean coal exports at $400.9 million or 7.5 million metric tons annually, whichever is lower, starting on January 1. Over the first 10 months of this year China has imported 18.6 million tons of coal from North Korea, up almost 13 percent from a year ago, according to Reuters.

Coal is one of North Korea's only sources of hard currency and its largest single export item. The draft UN resolution would also ban exports of copper, nickel, silver and zinc, which the U.S. official said is worth about $100 million a year.

The draft text would prohibit the sale of statues by North Korea, and would also prohibit countries from selling North Korea helicopters or vessels.