The Belt and Road Initiative, or BRI, should foster a rule-based environment, where legal obligations are met, transparency is promoted and the rule of law is sustained, said the United Nations' top legal officer.

"Enjoying growing mutual trust and exchanges at all levels can only be achieved with a solid legal framework," said Miguel Serpa Soares, under-secretary-general for legal affairs and UN legal counsel.

In office since September 2013, Soares oversees the UN's office of legal affairs, which provides legal services to the UN.

"Connecting dozens of countries with different legal systems and legal cultures has challenges derived from the need to balance the promotion of harmonization according to international standards and the preservation of the rich legal diversity of the countries involved," he said.

In an interview with China Daily, Soares said it is important that the convergence of legal traditions or commercial laws in nations along the BRI doesn't create obstacles to investment and trade.

Soares said his office supports the work of the UN Commission on International Trade Law, or UNCITRAL, which promotes the harmonization of commercial law for a sounder international business environment.

UNCITRAL legal standards are developed with participation from states and international governmental and non-governmental organizations.

In the context of BRI, several UNCITRAL tools can support the promotion of a regulated and law-based business environment, he said.

"They include international conventions - model laws and legislative guides covering the legal foundation for a good business environment," he said.

Soares said that "there are common principles to all legal traditions that characterize what fairness and justice represent for all of us".

China's development has been "an unprecedented achievement on so many fronts that is nothing short of commendable that this vast country looks at ways to share its success through the Belt and Road," he said.

"It is particularly noteworthy the importance that President Xi Jinping himself attaches to the rule of law and the fight against corruption," he said.