Amid uncertainties caused by Britain's decision to exit the European Union, leaders of the Group of 20 economies will likely renew their commitment to avoid new trade barriers for another two years, sources involved in preparations for the group's next summit said.

The leaders are set to make the promise of a freeze through 2018 when they meet in the Chinese city of Hangzhou in early September, senior officials taking part in the planning said recently.

"Under the current circumstances, it is meaningful and we should renew this pledge," Wang Xiaolong, China's special envoy on G-20 affairs, told reporters last week. The pledge is currently set to expire later this year.