Competition for water resources could provoke wars in Africa and the Middle East, Boutros Boutros Ghali has said.
The Blue Nile's source lies in Ethiopia, which uses almost none of its water
In an interview with the BBC, the former UN Secretary General urged the international community to ensure a fair division of water between nations.
Mr Boutros Ghali told Radio 4's Today programme that military confrontation between the countries of the Nile basin was almost inevitable.
It would only be avoided if they could share water equitably, he said.
Egypt has long been the greatest user of Nile water.
But countries upstream on both the Blue and White Niles are increasingly demanding a greater share.
Lake Tana in Ethiopia is the source of the Blue Nile, yet at present the country uses almost none of the river despite suffering increasingly frequent droughts, which result in crop failures that leave millions of people needing food aid to survive.
The Ethiopian government has complained that it has not yet received international support to enable it to exploit this natural resource while, downstream, Egypt is using the river to convert vast areas of desert into rich arable land.
Countries along the While Nile such as Kenya and Tanzania are also pressing for a greater share of the water that runs through their territory to Egypt.
But Mr Boutros Ghali says that Egypt would also need even more water in the future because of "a demographic explosion", which has already seen its population rise from 20 million people 50 years ago to 70 million today.
Mr Boutros Ghali, a former Egyptian foreign minister, said most Egyptians took their water supplies for granted and were largely ignorant of the problems they could face in years to come if the issue was not resolved.
"The security of Egypt is related to the relation between Egypt and Ethiopia, Sudan, Kenya and other African countries," he said.
"The real problem is that we need an additional quantity of water and we will not have an additional quantity of water unless we find an agreement with the upstream countries which also need water and have not used the Nile water until now."
He expressed the hope that international organisations, such as the World Bank, would mediate to ensure a peaceful outcome.
Mr Boutros Ghali has previously warned that water disputes could cause war in the Middle East.
Despite recent hopeful signs in the peace process, he said that a future Palestinian state would not be viable if so much of its water remained in Israeli control.
In a separate interview with the Today programme, Prince Hassan of Jordan said that the current situation was creating resentment that threatened to engulf the region in further violence.
"The ranks of the dispossessed, the misery they face will be a cause for greater bitterness and greater militancy and I can only see that we are hot-housing the kind of fury and rage that we claim we want to fight against," he said.
"And I think that the region is going to implode. People can put up with so much but they can not put up with injustice."