More than 30 archaeological shipwreck sites have been discovered off the country's shoreline, the national oceanic body has reportedly said.

The shipwrecks were discovered during a research project called 908, China News Service on Sunday quoted an unidentified official with the State Oceanic Administration's department of science and technology as saying.

The findings were released during a seminar on the project in Xiamen, Fujian province.

The research conducted by the administration between 2004 and 2009 covered 676,000 square kilometers of inland water and territorial sea.

Ancient merchants shipped vast stores of goods, including ceramics and bronze-wares, along the Maritime Silk Road.

"So there are plenty of underwater archaeological sites near southeast China's coast and around neighboring countries, such as Vietnam," Chinese Academy of Cultural Heritage researcher Sun Jian said.

The Maritime Silk Road is a sea route dating back to the Eastern Han Dynasty (AD 25-220), linking Quanzhou in modern Fujian province to India and the Red Sea to the Mediterranean.

"One ancient shipwreck usually abounds with tens of thousands of relics from the same dynasty," Sun said.

"The huge profits have enticed a growing number of fishermen to dive for these riches."

State Administration of Cultural Heritage official Chai Xiaoming said looting had undermined cultural relics' preservation.

Fujian police have launched crackdowns.

They uncovered 45 smuggling cases and seized 7,144 artifacts from shipwrecks in 2006.

They dealt with 25 cases and retrieved 2,700 relics in 2005, the Beijing-based China Culture Daily reported.

Sun, the researcher, said nearly all of the country's underwater archaeological sites are looted before excavation.

"In the 12th Five-Year Plan (2011-2015) period, we should protect underwater relics by strengthening the judicial system and developing stronger teams with cutting-edge technology," Tianjin Daily quoted Chai as saying on Saturday.

Currently, China does not have detailed laws protecting underwater cultural relics. The country has fewer than 100 certified archaeologists capable of underwater operations.