The head of the Muslim Brotherhood's Freedom and Justice Party (FJP) Mohamed El-Katatni told Al-Ahram's Arabic-language news website on Wednesday that a military response to Ethiopia's Nile dam project "cannot be taken without the consent and support of the Egyptian people."
Tension between Egypt and Ethiopia escalated last week after the latter began diverting the course of the Blue Nile – the source of the lion's share of Egypt's Nile water – as part of a project to build a series of dams along the river.
Ethiopia's Grand Renaissance Dam project has been a source of concern for the Egyptian government, which fears that the project – if completed – could negatively impact Egypt's traditional share of Nile water.
"Egyptians are peaceful by nature, but they have a historical entitlement to Nile water," El-Katatni, a former parliamentary speaker, was quoted as saying. "And it is their right to defend it by any means necessary."
Egypt, he added, had "several options" available to it to respond to recent moves by Ethiopia.
"The first option is the diplomatic approach. If this doesn't succeed we can resort to international arbitration," El-Katatni said.
"And if this doesn't succeed, we can ask regional and international organisations – such as the Arab League and the United Nations – to intervene," he added.
Earlier this week, the Egyptian presidency announced that Addis Ababa had failed to provide substantial information on the impact of the dam on downstream countries.
On Wednesday, a handful of Islamist parties – led by the Brotherhood's FJP – called for a 'national dialogue' to be held on Saturday to table proposals for resolving the issue.
The Brotherhood is the group from which Egyptian President Mohamed Morsi hails from.