China's "Belt and Road" initiative must be green and sustainable, President Xi Jinping said at the opening of a summit on his grand plan on Friday, adding that the massive infrastructure and trade plan should result in "high quality" growth for everyone.

Xi's plan to rebuild the old Silk Road to connect China with Asia, Europe and beyond with huge spending on infrastructure, has become mired in controversy as some partner nations have bemoaned the high cost of projects.

China has repeatedly said it is not seeking to trap anyone with debt and only has good intentions, and has been looking to use this week's summit in Beijing to recalibrate the policy and address those concerns.