BEIJING  - China's copper imports fell 3.1% in October from the previous month, customs data showed on Friday, as a cooling manufacturing sector in the world's top consumer of the metal kept demand subdued, while aluminium exports slipped to an eight-month low.

Arrivals of unwrought copper, including anode, refined and semi-finished copper products into China, were 431,000 tonnes last month, the General Administration of Customs said.

That was down from 445,000 tonnes in September but up 1.9% from 423,000 tonnes in October 2018.

Factory activity in China shrank for a sixth straight month in October, which features a week-long national holiday, an official survey showed, underlining the pressure on the copper-intensive manufacturing industry. 

"Demand remains weak, especially from the automotive sector," said He Tianyu, a copper analyst at CRU in Shanghai. Auto sales in China have fallen for 15 straight months, according to the China Association of Automobile Manufacturers. 

The air-conditioning sector, another key source of copper demand, is also not performing well, He added.

January-October imports of unwrought copper were down 10% year-on-year to 3.97 million tonnes, customs said.

Imports of copper concentrate, or partially processed ore, meanwhile came in at 1.914 million tonnes in October, the customs data showed. That was up 21.1% from 1.581 million tonnes in September and up 22% year-on-year as smelters stocked up on raw material.

January-October imports were up 8.3% year-on-year at 17.916 million tonnes.

The increase in concentrate imports comes as the copper smelters prepare for crunch talks with miners on 2020 supply deals in Shanghai later this month.

The high concentrate number will give miners confidence they can negotiate favourable treatment charges for copper concentrate next year, CRU's He said.

The charges, paid by miners to smelters to process ore into refined metal, go down when the concentrate market is tight.

China's aluminium exports edged down 0.9% in October from the previous month to their lowest since February.

The world's top aluminium producer, hit by two major smelter outages in August that are ongoing, last month exported 431,000 tonnes of unwrought aluminium, including primary metal, alloy and semi-finished products. 

The number compared to exports of 435,000 tonnes in September and was also down 10.6% year-on-year.

Jan-October aluminium exports were 4.8 million tonnes, up 1.4% from the same period last year, customs said.

(Reporting by Tom Daly; Editing by Kenneth Maxwell and Stephen Coates) ((tom.daly@thomsonreuters.com; +86 10 5669 2119;))