China's imports from its neighbour North Korea slowed in July while its exports to the sanctions-hit country dwindled after surging in recent months, according to official Chinese statistics.

Overall, bilateral trade between the two countries stood at $456 million last month, nearly seven per cent down from June, according to General Administration of Customs figures.

The decline is partly due to a steady decline in China's imports from North Korea, which fell to $156.3 million in July, down three per cent from the previous month and more than 30 per cent year on year.

China, the main ally of Pyongyang and the recipient of some 90 per cent of North Korea's exports, suspended all imports of coal in February in compliance with United Nations (UN) sanctions.

The aim of these restrictions is to deprive the Kim Jong-Un regime of crucial currency sources in order to check its controversial nuclear programme.

Following a seventh round of sanctions adopted in early August by the UN Security Council, Beijing recently announced it will also suspend its purchases of North Korea's iron, lead and seafood.

Chinese exports to the Stalinist regime fell to $299.8 million in July, down more than eight per cent from June.

But exports were up 55 per cent year on year. North Korea considerably increased its purchases from the Asian giant in recent months, including appliances, mechanical parts, textiles and solar panels.

In Dandong, a Chinese border town, AFP found last month that vibrant trade continued despite sanctions, with many Chinese shops continuing to offer jewels made of North Korean gold and silver, which have long been banned from the other side.

US President Donald Trump has urged China to step up pressure on its turbulent neighbour.

The Trump administration angered China this week by slapping punitive measures on several Chinese and Russian companies accused of supporting the North Korean nuclear programme and attempting to evade US sanctions.

The key targets were Chinese coal importers.