LUSAKA - Immigration authorities in Zambia on Tuesday released all the 31 Chinese nationals who were detained over the weekend.

The Chinese nationals, working for copper smelting Chinese companies on the Copperbelt province, were detained by police for suspected illegal purchase of copper tailing raw materials.

However, Zambia authorities have failed to provide strong proof of their crimes, and released the Chinese nationals after talks with the Chinese Embassy officials.

The Chinese nationals are expected to be flown back to China after their release, sources told Xinhua.

On Monday, China lodged solemn representations to Zambia following the detaining of its nationals.

While stating that China does not defend illegal actions, the Chinese Foreign Ministry expressed concern over "selective" law-enforcement against its citizens overseas.