MANILA, Philippines - The Chinese government on Friday urged the Philippines to free 80 Chinese miners who are being detained at their worksite amid an investigation into alleged illegal mining and mineral smuggling.

Wang Xiaobo, embassy consul at China's embassy in Manila, said mission staff had met Filipino officials to convey his government's request that the case be resolved quickly and that the workers be released.

"The Chinese embassy... lodged urgent representations to the Philippine side... (to) take effective measures to safeguard the personal safety and legitimate rights and interests of the Chinese workers, and lift the restrictions of their freedom of movement," Wang said in a statement.

Philippine soldiers, police and mining authorities raided the mine in Masinloc, a small town about 150 kilometres (90 miles), north of Manila on July 22 as part of a crackdown on illegal mining and exporting of chromite to China.

Police have since restricted the 80 Chinese to the mine site while immigration officials investigate the workers' travel papers. Police allege up to 70 of them did not have work visas.

Wang said embassy staff had met the Chinese workers and they were "safe and sound".

Zambales police spokesmen could not be reached for comment Friday.

Zambales police said earlier the mine was operated by a local firm, Companhia Minera Tubajon Inc. They alleged that it had been exporting large volumes of chromite to China without export permits.

However, Wang said the mine was run by a local company which he called Geoking Asia Mining Corp.

He said the raid may have been linked to a business dispute between Geoking and another local mining firm which he did not name.

Chromite is the ore for chromium, which is mixed with steel to make it harder and resistant to corrosion.