SIMIC

The new legislation - China's Personal Information Protection Law - came into effect on November 1, has added to a raft of new rules designed to increase government control over how domestic and foreign organisations collect and export China's data.

Although there are no specific guidelines on shipping data in the regulations some domestic providers in China have stopped giving information to foreign companies as a direct consequence of the new rules, the sources told Reuters.

The data is relied upon to provide information on cargo volumes and helps optimise logistics by predicting congestion so companies can make key decisions on shipping routes.

MarineTraffic, a top global provider of ship tracking and maritime intelligence, is among those foreign companies now experiencing gaps in vital shipping location data from China, where much of the world's supply of manufactured goods and some industrial commodities come from.

"If this continues, there will be a big impact in terms of global visibility especially as we come into the busy Christmas period with supply chains already facing huge problems all over the world," said Anastassis Touros, AIS network team leader at MarineTraffic.

"All of a sudden we do not know when ships are leaving and from where, and we also don't have the full picture on port congestion which AIS offers us."

The so-called Automatic Identification System (AIS) provides the locational positions on ships. It is used by other vessels, ports, and many other organisations from banks and traders to search and rescue operations.

From October 28 to November 15 the level of terrestrial shipping data across all Chinese waters was estimated to have dropped 90 per cent according to market intelligence and valuations provider VesselsValue.

Two other sources put the drop in terrestrial AIS data at up to 45 per cent in recent days.

An official with the Guangdong Maritime Safety Administration told Reuters that AIS rules were set by the department's headquarters in Beijing. Calls to the Maritime Safety Administration's Beijing office were not answered.

Other Chinese officials did not immediately respond to requests for comment.

A spokesperson with UN agency the International Maritime Organization, which adopted global AIS regulations, had no comment when contacted.