Ethiopia's decision to build the Grand Renaissance Dam challenges a colonial-era agreement that gives downstream Egypt and Sudan rights to the Nile water, with Egypt taking 55.5 billion cubic meters and Sudan 18.5 billion cubic meters of the total of 84 billion cubic meters, with 10 billion lost to evaporation. That agreement, first signed in 1929, took no account of the eight other nations along the 6,700-kilometer  river and its basin, which have been agitating for a decade for a more equitable accord.

Ethiopia's unilateral action appeared to ignore the 10-nation Nile Basin Initiative, a regional partnership formed in 1999 that seeks to develop the river in a cooperative manner.

Ethiopia is leading a group of five nations threatening to sign a new cooperation agreement known as the Entebbe Agreement without Egypt and Sudan, effectively taking control of the Nile, which serves some 238 million people.

In another blow to Egypt, newly independent South Sudan said it would join the new group.

"South Sudan has no choice but to become a member of the Entebbe Agreement," Foreign Minister Deng Nhial Deng told reporters, adding that his government had informed Egypt of the decision. He said South Sudan is envisioning long-term projects that it expects will face opposition from Egypt.

From The Associated Press