GUANGZHOU, Dec. 11 -- A New Zealand man has been held in south China's Guangdong Province for allegedly attempting to smuggle 30 kg of crystal methamphetamine out of the country, local customs authorities said Thursday.

It is the largest ever crystal meth smuggling case Guangdong customs have seen, Rao Jiyong, a customs official, told a press briefing.

An Australian woman, who entered China with the man on tourist visas, has been released after investigation showed that she was not intentionally involved.

The case was cracked on Nov. 8 when the two tried to board a plane back Sydney from Guangzhou, capital of Guangdong, and customs officers found 30 kg of the drug, in their luggage.