Makhyoun said Ethiopia is "fragile" because of rebel movements inside the country. "We can communicate with them and use them as a bargaining chip against the Ethiopian government," he said.
"If all this fails, then there is no choice left for Egypt but to play the final card, which is using the intelligence service to destroy the dam," said Makhyoun, whose Nour party won about 25 percent of parliament's seats in elections in late 2011 and early 2012.
Another politician, liberal Ayman Nour, proposed spreading rumors about Egypt obtaining refueling aircraft to create the impression that it plans an airstrike to destroy the dam.
"This could yield results on the diplomatic track," Nour said.
Abu al-Ila Madi, leader of the pro-Morsi Islamist Wasat party, suggested that a rumor that Egypt planned to destroy the dam could scare the Ethiopians into cooperating with Egypt on the project.
Magdy Hussein, another Islamist politician, warned that talk of military action against Ethiopia is "very dangerous" and will only turn Ethiopians into enemies. He suggested soft diplomacy in dealing with the crisis, including organizing a film festival in Ethiopia and dispatching researchers and translation missions.