The two-day meeting included Presidents Vladimir Putin of Russian Federation and Recep Tayyip Erdogan of Turkey and presidents or prime ministers from Italy, Hungary, Greece, Kenya and most of China's Asian neighbors but no major Western leaders.
Seeking to portray the initiative as welcoming and inclusive, Xi promised to avoid forming a "small group" of allies, which he said might harm regional stability.
"The Belt and Road initiative aims to increase worldwide cooperation on the basic principles of mutual discussion, mutual construction and mutual sharing", he said, adding that the initiative, which is now in its fourth year, has made significant strides in advancing global cooperation.
China formally calls the scheme the Belt and Road initiative in English.
Why: The plan calls for the creation of worldwide trade, infrastructure and finance links.
The China Development Bank has earmarked US$890 billion for some 900 projects.
"To Trump, this may appear to be a cheap solution to filling the hole that, he now discovers, his TPP decision has left". Putin also called for scientific cooperation and to "set up global laboratories" which can contribute to regional development.
"Trade is the important engine of economic development", Mr Xi said at a summit of world leaders in Beijing.
Mr Xi also proposed the creation of a new platform for close coordination between multilateral development financing institutions.
Pakistan has been a flagship country and one of the most enthusiastic supporters of the One Belt-One Road initiative, in part because many projects are for power plants to alleviate the country's decade-long energy-shortage crisis that sees frequent blackouts.
"It must also be clear what is actually going to be built".
Human Rights Watch raised concerns on Saturday about the treatment of people along the new Silk Road route in Central Asian nations with poor track records in infrastructure projects.
Chinese officials insist the initiative is purely commercial, but foreign diplomats and political analysts also see an effort by Beijing to promote its own vision of trade and security arrangements and reduce the US presence in Asia.
According to Chinese government officials, at least 28 Heads of State and Government from around the world, including the presidents of Ethiopia and Kenya, are expected to attend the two-day forum in Beijing. China has been accused by critics of crafting procurement rules for cross-border projects in a manner that means the bulk of deals and machine supply orders go to Chinese companies. "It must not be politicized", he said here on the opening day of the event. She called for joint planning for infrastructure projects by all stakeholders instead of leaving it to one sponsor or country. There was a need to "involve the private sector on the basis of fair and transparent participation", she said.
He added that the initiative would open up Rwanda to the world more than ever before.
Mr. Xi said the new Silk Road would be open to all, including Africa and the Americas, which are not situated on the traditional Silk Road.
The initiative spans some 65 countries representing 60 percent of the world population and around a third of global gross domestic product.
The project - where Kenya is seeking partnership with the private sector to build a highway, an oil pipeline, a railway line and a sea port at Lamu connecting South Sudan and Ethiopia, - is created to link up with another corridor from West Africa.
A clear indication of India's boycott came last night in an official statement that said India can not accept a project that violates its sovereignty and territorial integrity.
Prime Minister Nawaz Sharif said on Monday Pakistan and China will decide whether to add any country in China-Pakistan Economic Corridor, reported Dunya News.
People take pictures in front of a "Golden Bridge on Silk Road" installation, set up ahead of the Belt and Road Forum, outside the National Convention Centre in Beijing, China May 11, 2017. But governments have expressed concern Beijing might use "Belt and Road" to promote Chinese exports by encouraging its neighbors to adopt China's industrial standards for railways and other goods. The China-Laos railway is under construction and work on the China-Thailand railway is being accelerated. "China has learned this lesson well and so has Africa", said the President.
"This is a continuation of Chinese non-interference", Economist Suman Bery said.