UPDATE 2-China copper imports jump 19 pct in May, concentrate shipments surge

* Copper imports rise 19.4 pct in May on year

* Jan-May copper imports jump 22 pct

* China copper concentrate imports surge 45 pct on year

* Aluminium exports at 420,000 tonnes, up 5 pct on month (Adds copper concentrate imports, comment)

SHANGHAI, June 8 (Reuters) - China’s copper imports jumped 19.4 percent from the same month a year ago to 430,000 tonnes in May, customs data showed on Wednesday, swelling already ample supply that is expected to reduce metal imports in coming months.

Shipments into China have remained strong this year - up 22 percent over the first five months - after a weaker dollar boosted Chinese purchasing power, swelling exchange and bonded inventories. Exchange stockpiles hit record highs in March.

At the same time, China’s smelters have ramped up imports of copper concentrate and restarted production as an increase in global mine supply has allowed them to raise their processing fees.

Copper imports in May slipped 4.4 percent from April, while imports of copper concentrate for use by smelters jumped 13 percent on the previous month and were up 45 percent from a year ago.

“Overall, we expect China’s copper imports to ease further in June as rising treatment and refining charges (TC/RCs) and domestic smelting production will increase domestic supply and reduce import demand,” Argonaut Securities said in a note.

Last week, China’s Jiangxi Copper and global miner BHP agreed to TC/RCs of $100 tonne and 10 cents a pound, above terms agreed in December by Jiangxi and miner Antofagasta for $97.35 a tonne and 9.735 cents a pound for the full year of 2016.

For the first five months of the year, China’s copper concentrate imports rose 34 percent on a year go to 6.7 mln tonnes.

Rising supply has hurt the demand for spot refined copper, already hampered by a slowing economy in the world's top producer of the metal. Premiums for spot copper in Shanghai's bonded zones reached four-year lows of $45 a tonne this week. CU-BMPBW-SHMET

Chinese traders have shifted surplus copper to Asian warehouses, depressing global prices.

The customs data also showed China increased its aluminium exports in May to 420,000 tonnes of unwrought aluminium and aluminium products, up 5 percent from April and 2.4 percent from the same month a year ago.

The rise in exports confirmed smelters are restarting in response to a price recovery, Argonaut Securities said.

“The rebound in aluminum exports has reignited concern about China flooding global markets with its excess supply, weighing on aluminium prices,” it said.

Aluminium exports were still down 7.9 percent at 1.9 million tonnes for the first five months of this year.

U.S. and China officials failed to reach an agreement this week on how to address excess global aluminium capacity, but will continue to hold discussions on the matter, senior officials said in Beijing this week.

Reporting by Ruby Lian in SHANGHAI; Additional reporting by Melanie Burton in MELBOURNE; Editing by Christian Schmollinger