Rio 'very concerned' about staff

Rio Tinto is a major supplier of minerals to China

Rio Tinto has said it is "very concerned" about its four employees detained in Shanghai amid accusations of bribery and spying.

The company said the allegations are "wholly without foundation".

Stern Hu, an Australian, and three of the firm's other employees were detained in China last week.

The detentions come amid negotiations about iron ore prices between Australia and China and has cast a shadow on relations between the two countries.

"Rio Tinto believes that the allegations in recent media reports that employees were involved in bribery of officials at Chinese steel mills are wholly without foundation," Sam Walsh, chief executive of Rio Tinto's Iron Ore division, said.

"We remain fully supportive of our detained employees, and believe that they acted at all times with integrity and in accordance with Rio Tinto's strict and publicly stated code of ethical behaviour," he added.

Scrapped merger

The company said it continued to operate in China and is maintaining iron ore shipments from Australia.

Earlier this week, China extended its investigations into alleged spying and bribery by Rio Tinto employees to executives at five Chinese steelmakers.

Officials at Baosteel Group, Anshan Iron & Steel Group, Laigang Group and Jigang Group are being questioned.

Analysts say the allegations have cast a shadow over resource-rich Australia's trading relationship with China.

In June, Rio scrapped a $19.5bn (£12.1bn) deal with China's state-owned Chinalco in favour of a tie-up with rival giant BHP Billiton, which angered some in Beijing.