In his opening remarks at the forum, Xi pledged an astounding US$124 billion to the new Silk Road plan, reinforcing that everyone was welcome to join what he envisioned would be a path to peace and prosperity for the world.
The remarks by Brigette Zypries were some of the most outspoken by a government minister as leaders from 29 countries gathered for the forum.
Xi said the initiative focuses on the Asian, European and African nations, but is open to all other countries. The China Development Bank has earmarked US$890bil (RM3.8 trillion) for some 900 projects.
Governments from Washington to New Delhi worry that Beijing is using the initiative to build its own political influence and erode theirs, or that China might undermine environmental standards or leave poor countries burdened with debt.
Kenya's President Uhuru Kenyatta (second left) and his wife Margaret Kenyatta (left) pose with Chinese President Xi Jinping and his wife Peng Liyuan during a welcome ceremony for leaders attending the Belt and Road Forum, in Beijing's Great Hall of the People on May 14, 2017.
A number of leaders including Russian President Vladimir Putin and Turkish counterpart Recep Tayyip Erdogan applauded the initiative, which Mr Xi unveiled in 2013 and hailed as "a project of the century".
The 45-minute-long address by the 63-year-old Chinese president came a day after India made it clear that it will not attend the two-day B&R Forum that began in Beijing today.
Ms Zypries called for "a transparent procurement process and adherence to worldwide standards" on the lines of Organisation for Economic Co-operation and Development members' consensus on export financing. Venezuela, which boasts friendly relations with China, is slated to expand economic ties with nations participating in the Belt and Road Initiative.
He added that the initiative would open up Rwanda to the world more than ever before.
He also pledged $8bn in aid to developing countries and worldwide organization along the belt and road for education and humanitarian work.
Bangladeshi experts, who highly lauded China's contribution to socioeconomic development of the world, said the initiative of reviving the ancient Silk Road through a network of roads and maritime waterways will surely be a boon for cooperation between China and the rest of the world.
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.
He declined to comment on the value of the investment but said that China's Lianyungang port will also invest in the project, which borders China's far western Xinjiang region.
A spokesman for its foreign ministry also said there were concerns about host countries taking on too much debt to fund Silk Road infrastructure.
"This will not overshadow (the summit) in an enormous way but it will absolutely continue to raise U.S. frustrations with Beijing", he said, adding that Washington was "frustrated" that North Korea was also invited to the summit. "It is really grounded in certain objectives such as economic and financial realities", Rehman said.