Premier Li Keqiang said the door to the world will become ever wider as the central government continues to expand opening-up.

"China welcomes enterprises from all over the world to seize the opportunities brought by greater opening-up, to expand cooperation and better achieve win-win results," Li said in a congratulatory letter saluting the BASF smart Verbund petrochemical project in Zhanjiang, Guangdong province, over the weekend.

Li said China will accelerate the building of a market-oriented, international business environment based on the rule of law and give equal treatment to domestic and foreign-funded enterprises of different ownership types.

The first large petrochemical project solely owned by foreign investors in the country, the project illustrates that opening-up measures are being implemented, and that Sino-German cooperation in the manufacturing sector is being taken to a new level, Li wrote.

The German word Verbund means integrated and connected. By carefully designing plants and processes, the byproducts of one plant become feedstock for an adjacent plant, and heat released from one chemical reaction becomes the energy that drives the next, the company said.

Li's congratulatory letter was read out by Ning Jizhe, vice-minister of the National Development and Reform Commission, on Saturday.

In its 2019 negative list for market access, China reduced the number of sectors and businesses that are off-limits for domestic and overseas investors.

The shortened list, released by the NDRC and the Ministry of Commerce on Friday, contains 131 administrative measures regarding investment, down 13 percent from the 2018 version.

German Chancellor Angela Merkel also sent a congratulatory letter saluting the commencement of the mega project. China is of great importance to the German economy and last year was again Germany's most important trading partner, Merkel said, noting that Germany's investment in China is also continuing to grow.

The decision by BASF to set up one of its largest plants in Guangdong is another milestone in German-Chinese economic relations, she said.

In July last year, Li and Merkel witnessed the signing of a memorandum of understanding on the smart verbund project between Guangdong province and BASF.

With the commencement ceremony, the German chemical giant officially launched the $10 billion project and the construction of its first plants in Zhanjiang.

The ceremony was attended by senior officials from the central government and Guangdong province, along with German consular officers and senior BASF executives.

The first plants will produce engineering plastics and thermoplastic polyurethane to serve the increasing needs of various growth industries in the southern China market and throughout Asia.

"We are pleased to see that our mega investment project in China is progressing," said Martin Brudermuller, chairman of the board of executive directors for BASF SE.

"We are determined to support our customers in southern China in driving growth with innovative products and sustainable solutions," he said. "By utilizing the latest digital technologies and applying the highest safety standards, the new Verbund site will be a role model for sustainable production that contributes to the development of a circular economy in China."

Stephan Kothrade, president and chairman of BASF China, said Zhanjiang is a perfect location for BASF to further widen its production footprint.

"The smart Verbund site will form a solid foundation for a world-class industrial cluster in Zhanjiang and establish stronger business connections between South China and other Asian countries," he said.

The site in Guangdong will be BASF's largest investment and will be operated solely under the oversight of BASF.

The site will ultimately be the third-largest BASF site worldwide, following Ludwigshafen, Germany, and Antwerp, Belgium.