China's trade with North Korea fell in July from a month earlier, data showed on Wednesday, as a ban on coal purchases from its isolated neighbour slowed imports amid growing pressure from the United States to rein in Pyongyang's missile programme.

The world's second-largest economy imported and exported goods worth $456 million in July, down from $489 million in June, according to data from China's General Administration of Customs.

It was up from $426 million in July last year, according to data on the customs website.

Year-to-date, trade was up 10.2 percent at $3.01 billion.

The data indicates that China's move to halt North Korean coal imports in February has crimped Pyongyang's ability to raise hard currency through exports.

Iron ore arrivals from North Korea in July also sank to their weakest since February, while China's gasoline exports to the isolated state hit their lowest since January 2016.

China's imports from North Korea were $156 million, down 3 percent from last month and a third lower than a year ago, based on data on the customs website. For January-July, imports were $1.04 billion, down 16.3 percent.

Exports were $300 million, down from $327 million in June, but up from $194 million in July last year. Year-to-date, they were up a third at $1.97 billion.

On August 6, the United Nations Security Council unanimously imposed new sanctions on North Korea banning exports of coal, iron, iron ore, lead, lead ore and seafood, in a bid to choke off a third of Pyongyang's $3 billion in annual export revenue.

The crackdown on major commodity exports was aimed as punishment for intercontinental ballistic missile (ICBM) tests in July and is due to take effect in early September.

Last week, Beijing issued an official ban on the imports effective from Aug. 15 as it moved to implement the sanctions.

Sources told Reuters China was also pressuring its iron ore traders to stop buying the commodity from North Korea, tightening the screws on leader Kim Jong-un even before sanctions.

The data also comes after state-owned China National Petroleum Corp suspended sales of fuel to North Korea in June over concerns it wouldn't get paid, cutting off crucial supplies. The suspension is still in place.

These kinds of actions have been at the centre of US President Donald Trump's calls for Beijing to exert more economic and diplomatic pressure on North Korea to help rein in its nuclear and missile programmes.

On Tuesday, the United States imposed new sanctions, targeting Chinese and Russian firms and individuals for supporting Pyongyang's weapons programs.