Agreements between countries that share the same river have helped to avoid about 1,800 conflicts in the past 50 years, the World Water Council (WWC) said.

The accords were designed to ensure that what happens upstream does not harm countries downstream, Benedito Braga, WWC president, said on the sidelines of the 8th World Water Forum in Brasilia on Thursday.

"Rivers that run through more than two countries have to be shared between these countries," he said at the forum, whose slogan is "sharing water."