China defended Thursday its purchase of iron ore from North Korea following criticism by US President Donald Trump and said it is "strictly and earnestly'' complying with U.N. sanctions.

China stopped importing North Korean coal but total trade has risen, which prompted Trump to complain last week Beijing is failing to use its economic leverage to stop Pyongyang's pursuit of nuclear weapons.

Chinese purchases of North Korea iron ore rose 34 percent from a year earlier in the first five months of the year, according to a South Korean industry group, the Korea International Trade Association. Iron ore is among China's biggest imports from the North after it stopped buying coal this year due to the sanctions.

Such purchases are permitted under the sanctions and generate no revenue for nuclear development, said a foreign ministry spokesman, Geng Shuang.

"We will continue to strictly and earnestly implement the North Korea-related Security Council resolution in its entirety," said Geng at a regular news briefing.

"We hope all relevant sides can make sure that they are clear that Security Council sanctions imposed on North Korea are not comprehensive economic sanctions."

China has long been the North's main diplomatic defender but increasingly expresses frustration with leader Kim Jong Un's provocative behavior.

Beijing agreed in March 2016 to enforce U.N. sanctions following North Korea's test of a missile possibly capable of carrying a nuclear warhead. But Chinese leaders are reluctant to push Pyongyang too hard for fear Kim's government might collapse. They argue against disrupting trade in food and other goods that might cause public hardship.

Last week, Trump cited a Chinese Customs agency statement that two-way trade with North Korea rose 36.8 percent from a year earlier in the first quarter. He complained that indicated Beijing was failing to do enough.

Total Chinese imports from North Korea declined 13.2 percent in the first half of the year compared with a year earlier to $1.7 billion, while exports to the North rose 29.1 percent to $880 million, the Chinese Customs agency reported Thursday.

Chinese imports of North Korean coal in the first half fell 75 percent to 2.7 million tons from a year earlier following the suspension in February, according to Huang Songping, a Customs agency spokesman.

Huang said month-on-month figures showed an even sharper decline. He said Chinese imports from the North fell 36.5 percent in March, 41.6 percent in April and 31.6 percent in May.

"Trade related to the people's livelihood in North Korea, especially if it embodies humanitarian principles, should not be affected by sanctions," said Huang at a separate news briefing. (AP)