After months of wrangling, the U.N. Security Council is prepared to impose new, tougher sanctions on North Korea over its fifth and largest nuclear test yet, diplomats said Monday.

U.S. officials who declined to be identified because the Security Council resolution has not yet been made public said that if the text is adopted and fully implemented it would mark "a significant step forward," in the sanctions regime against North Korea over its nuclear program.

The U.S. and other veto-wielding permanent council members — Russia, China, Britain and France — have been negotiating the new sanctions for months in response to North Korea's Sept. 9 nuclear test.

Officials said they expect the council to vote on the resolution, which for the first time places a hard cap on North Korean coal exports, on Wednesday morning.

The new sanctions target North Korea's hard currency revenues by placing a "hard, binding cap" on coal exports, cutting them by at least 62 per cent, capping them at around $400 million or 7.5 million tons, diplomats said. According to the Global Trade Atlas, China is on track to import nearly $1 billion worth of coal from North Korea in 2016 despite a previous sanctions regime.

Diplomats said the new sanctions further clarify that the "livelihood" exemption, which allowed the Chinese imports, is meant only to protect the livelihoods of those currently living inside North Korea, not Chinese people or companies doing business with the country.

The sanctions would also slap a ban on North Korea's exports of non-ferrous metals and sanction 11 government officials as well as 10 entities linked to the country's nuclear weapons program.

North Korea conducted its fifth atomic test, boasting of a technologically game-changing nuclear technology, in defiance of both tough international sanctions and long-standing diplomatic pressure to curb its nuclear ambitions.

North Korea's persistent pursuit of missiles and nuclear weapons has long been one of the most intractable foreign policy problems for U.S. administrations.

Diplomacy has so far failed. Six-nation negotiations on dismantling North Korea's nuclear program in exchange for aid were last held in late 2008 and fell apart in early 2009.

The Korean Peninsula remains technically at war, as the 1950-53 Korean War ended in an armistice, not a peace treaty.

News from © The Associated Press, 2016