China has denied violating UN limits on oil supplies to North Korea after the US president criticised Beijing for allowing oil to get there.
It comes as South Korea said it had seized a Hong Kong-flagged vessel suspected of transferring oil to a North Korean vessel at sea.
Beijing has “completely and strictly” complied with sanctions meant to discourage leader Kim Jong Un’s government from pursuing nuclear and missile technology, foreign ministry spokeswoman Hua Chunying said.
A South Korean newspaper said this week that ships believed to be Chinese transferred oil to North Korean vessels at sea.
Donald Trump said on Twitter he was “very disappointed that China is allowing oil to go into North Korea”.
China is North Korea’s main trading partner and energy supplier. The UN sanctions allow limited supplies of oil but prohibit transfers of any goods to North Korean vessels at sea.
Beijing, long North Korea’s main diplomatic protector, has expressed growing frustration with its nuclear and missile tests.
It supported the latest sanctions but argues against any steps that might harm the North’s public or destabilise its government.
“China has been completely and strictly implementing Security Council resolutions and fulfilling our international obligations,” Ms Hua said.
“We will never allow Chinese citizens and enterprises to engage in activities that violate Security Council resolutions.”
She said authorities investigated a report a Chinese ship transferred oil to a North Korean ship at sea on October 19 and concluded it was false.
The US Treasury Department released satellite photos in November that showed what it said was a North Korean ship receiving oil from an unidentified vessel on that date.
Those images received wider public attention this week when Chosun Ilbo reprinted them to accompany the report that ships believed to be Chinese had transferred oil to North Korean vessels some 30 times since October.
On Friday, South Korean authorities said they seized a Hong Kong-flagged vessel suspected of transferring oil to a North Korean vessel at sea on October 19.
The Lighthouse Winmore is believed to have transferred about 600 tons of refined petroleum products to the Sam Jong 2 after leaving the South Korean port of Yeosu, the South Korean government said.
The ship was seized when it returned to Yeosu.
In response to a question about Mr Trump’s comments, Ms Hua said: “The relevant ship, since August, has never docked at Chinese ports, and there is no record showing it has left or entered Chinese ports.
“I am not aware of whether the ship has visited other countries’ ports. So, the relevant report is not consistent with the fact.”
It wasn’t immediately clear whether the Lighthouse Winmore was involved in the transactions shown in the Treasury images.
In a commentary published on Thursday, US Secretary of State Rex Tillerson urged Beijing to exert “decisive economic leverage” on Pyongyang.
“China has applied certain import bans and sanctions, but it could and should do more,” he wrote in The New York Times.
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