Chinese Vice Premier Zhang Gaoli (left) shakes hands with UN chief Ban Ki-moon at the UN headquarters in New York, the United States, April 21, 2016. Photo/Xinhua

China will formally ratify the Paris Agreement before September, said Vice-Premier Zhang Gaoli, who signed the climate agreement on behalf of President Xi Jinping on Friday at a special ceremony at the United Nations.

Zhang, Xi's special envoy, also called on all G20 members to give early approval to the agreement.

"China will finalize domestic legal procedures on its accession before the G20 Hangzhou summit in September this year," said Zhang to applause from the audience.

More than 175 countries signed the agreement on Friday. It was a new record for the most countries to sign an international agreement on one day, which had been set in 1982 when 119 countries signed the Law of the Sea Convention.

"Today is a day that I have worked toward since day one as secretary-general of the United Nations and declared climate change to be my top priority. Today you are signing a new covenant with the future," said UN Secretary-General Ban Ki-moon, who will step down at the end of this year after 10 years in the post.

"Today's record-breaking number of signatures on the climate change agreement sends a powerful message to the international community. It's now time to take action for humanity," said Ban.