BEIJING -- Chinese President Xi Jinping on Thursday pledged that China's door of opening-up will only open wider, and will never be closed.

He made the remarks while delivering a keynote speech at the opening ceremony of the Second United Nations Global Sustainable Transport Conference via video link in Beijing.

Xi said China will continue to hold high the banner of true multilateralism, and stay connected with the world and abreast with the times.

"This way, we will contribute more to global development while pursuing our own development," he said.

China will not change course in its pursuit of a new system of open economy of higher standards, nor will it waver in its resolve to promote trade and investment liberalization and facilitation, Xi said.