Aluminum Corp of China (Chalco), the country's largest smelter of the lightweight industrial metal, said its non-executive director and vice-chairman, Sun Zhaoxue, has resigned after the mainland's anti-graft watchdog said he has been detained to assist its investigation.

A series of investigations involving executives of major state-owned enterprises underscores Beijing's seriousness in cracking down on corruption and tackling vested interests.

A senior manager of Aluminum Corp of China (Chalco), the country's largest smelter of the lightweight metal, has become the latest in a series of high-level executives at central government-administered enterprises to be investigated by Beijing.

Aluminium Corp of China (Chalco), the nation's largest smelter of the lightweight industrial metal, warned of more tough times for the industry as it said its interim net loss narrowed, largely on the back of one-off gains and government subsidies.

Investor Mark Mobius said Aluminum Corp of China is a "good long-term bet" as one of the few producers of the metal set to benefit from the government's plans to reduce overcapacity.

Aluminum Corporation of China (Chalco) posted its worst results since going public in 2001, chalking up a net loss of 8.23 billion yuan (HK$10.18 billion) for last year.

Hong Kong's benchmark Hang Seng Index will no longer include the loss-making state-owned enterprise Aluminum Corp of China, also known as Chalco, but will add computer manufacturer Lenovo, Hang Seng Indexes said in a quarterly review yesterday.

While the pickup in the mainland's economy would see higher demand and product prices this year, analysts expect the firm to remain in the red, although the loss would be narrower.