Archaeologists have found two shipwrecks deep in the South China Sea, which serve as a witness to commercial and cultural exchanges along the ancient Maritime Silk Road.

The findings were announced in Beijing on Thursday at a news conference held by the National Cultural Heritage Administration.

The latest underwater archaeological explorations were carried out in September and October by the administration's National Center for Archaeology, the Institute of Deep-Sea Science and Engineering, the Chinese Academy of Sciences and the China (Hainan) Museum of the South China Sea.

Along with the shipwrecks, pottery, porcelain and ironware have been found, and nearly 600 artifacts have been recovered so far, most of which were produced at kilns in Jingdezhen, Jiangxi province, which is known as China's "porcelain capital".

The locations of the shipwrecks and the cultural relics were confirmed as a result of oceanographic detection and underwater investigations using manned submersibles that dived 41 times this year, said Song Jianzhong, a researcher at the National Center for Archaeology.

Techniques such as 3D photography and laser scanning were used during the investigations, added Song.

The No 1 shipwreck, from the reign of Emperor Zhengde (1506-21) of the Ming Dynasty (1368-1644), is about 37 meters long and 11 meters wide. So far, 543 artifacts have been recovered from the shipwreck.

Based on studies of the ship and its cargo, archaeologists speculated that it set off from a port in Fujian or Guangdong province and was bound for Malacca or another trade hub in Southeast Asia.

The No 2 shipwreck dates from the reign of Emperor Hongzhi (1488-1505). It measures about 21 meters long and 8 meters wide. A total of 36 artifacts, including processed logs, porcelain and pottery have been discovered on it.

The shipwrecks are located on the routes of expeditions led by renowned Chinese mariner Zheng He in the early Ming Dynasty.

Studies found that both ships were engaged in private maritime trade.

Restrictions on maritime trade were adopted in the middle of the Ming Dynasty, and such trade at the government level shrank a lot. However, private trade continued to prosper during this period, Song said.

"Discoveries from the two shipwrecks reflect the prosperity of maritime trade in the middle of the Ming Dynasty," he said. "These help us explore and understand the two-way flows of ships on the ancient Maritime Silk Road and maritime civilization in China."

Jiang Bo, a professor at Shandong University's School of History and Culture, said these discoveries are world-class and show that China's underwater archaeology has reached the deep sea.

"This is one of the most important archaeological programs in South China Sea archaeology and studies on the Maritime Silk Road, and is a perfect combination of underwater archaeology with manned submersible technology," said Jiang.

Archaeological researchers are now summarizing their experience and establishing standards in terms of technical regulations, methods, requirements and working procedures for deep-sea archaeology.

"It's totally new for us, and a big challenge," said Song.

Wang Guangyao, a researcher at the Palace Museum in Beijing, said that the latest findings shed new light on the study of China's porcelain-making history.

For example, the quality of Longquan Kiln porcelain, which was mainly exported from Zhejiang province, was previously thought to have sharply declined in the late 15th century. However, the discovery of a large number of fine Longquan celadon artifacts in shipwreck No 1 has led people to reconsider this notion, Wang said.

The next underwater archaeological study of the two shipwrecks will be conducted in March and April, according to Song.