Ethiopia's parliament has ratified a controversial treaty that would replace colonial-era agreements that give Egypt and Sudan the majority of water rights to the Nile River.
The 547-member parliament voted unanimously for the treaty, on Thursday, in spite of an ongoing dispute with Egypt over Ethiopia's construction of a massive hydroelectric dam on a Nile tributary.
The two countries have had a series of irate exchanges over the nearly $5 billion dam. Egyptian officials fear the so-called Grand Ethiopian Renaissance Dam will threaten their country's water supply.
With Thursday's vote, Ethiopia became the sixth country to back a new cooperative agreement that calls for establishing a commission to oversee Nile projects.
Rwanda, Burundi, Kenya, Tanzania and Uganda have already signed the agreement. Egypt is among several nations that have yet to do so.
The majority of Nile river water originated in Ethiopia. However, colonial-era treaties written by Britain gave Egypt and Sudan the bulk of the water.
The agreements gave Egypt as much 87-percent of the Nile's flow.
In May, Ethiopia began diverting water from a Nile tributary for construction of the dam.
Ethiopian officials say Egypt can make up any reduction with better water management.
On Monday, Egyptian President Mohammed Morsi said he was not calling for war, but warned that "all options" were open concerning his country's possible reaction to the dam project. Ethiopian officials responded, saying they were ready to defend the dam project.