Beijing: China told its companies on Friday they need to pay attention to the latest UN sanctions on North Korea, especially those related to coal, to avoid any unnecessary economic losses.

The U.N. Security Council imposed new sanctions on North Korea last month aimed at cutting its annual export revenue by a quarter, after Pyongyang carried out its fifth and largest nuclear test so far in September.

The 15-member council unanimously adopted a resolution to slash North Korea`s exports of coal, its biggest export item, by about 60 percent with an annual sales cap of $400.9 million, or 7.5 million metric tonnes, whichever is lower.

The U.S.-drafted resolution also bans North Korean copper, nickel, silver and zinc exports - and the sale of statues. Pyongyang is famous for building huge, socialist-style statues which it exports mainly to Africa.

Despite its recent anger at Pyongyang`s nuclear and missile tests, Beijing remains North Korea`s most important economic and diplomatic backer and it frequently comes under suspicion for not properly enforcing sanctions, something China denies.

China`s Commerce Ministry said in a statement on its website that "relevant companies" should pay close attention to the sanctions and restrictions, especially on coal.

"Understand the United Nations circular about North Korean coal exports, make preparations in advance and rationally arrange imports to avoid unnecessary losses," it said.

China is believed to be the only country buying North Korean coal, one of North Korea`s only sources of hard currency.

The ministry also reminded companies about the ban on imports of copper, silver, the other metals and statues, but imports which had already arrived in China would not be affected.