By Francis Markus BBC Shanghai correspondent

Chinese police say they have made their biggest single seizure of pirated pornographic video discs, totalling more than five million.

The haul was intercepted off the coast of Guangdong province, east of Hong Kong.

The quantities of pirated video discs being regularly seized by the Chinese authorities have become mind-bogglingly large.

The discs, DVDs and VCDs, were confiscated off two vessels after a tip-off.

One of the ships had already been abandoned by the smugglers.

Local officials are not saying where the vessels had come from, but the most likely source is Hong Kong, where the cost of pirating discs is still much lower than in mainland China.

'Hello, DVD'

It is a thriving trade. A visit to any city market is likely to yield approaches from local vendors with the standard greeting, "Hello, DVD, VCD."

In one such place, a foreign reporter was taken to a small room in a nearby house where three or four young men were selling from a trunk full of pirated Hollywood and other movies.

The vendor said pornographic ones were also available.

WTO rules

China's membership in the World Trade Organisation commits it to strengthening its measures to safeguard intellectual property, and the authorities often publicly destroy confiscated discs.

But pirated films are nonetheless openly available even in respectable city stores, while the official media frequently report concerns about pornographic material spreading, particularly among the country's young people.