Influential Egypt-born cleric Yusef al-Qaradawi, who is based in Qatar, on Sunday urged Egyptians to boycott the upcoming presidential election, saying ex-army chief Abdel Fattah al-Sisi took power "unfairly".
The then head of the Egyptian military, Sisi toppled Islamist president Mohamed Morsi last July, and is widely expected to win this month's presidential election.
"Sisi deposed the elected president and took power unfairly. How can we elect him?" the cleric told AFP.
Qaradawi is seen as a spiritual guide to the Muslim Brotherhood, the group Morsi hails from. He had issued a fatwa urging Egyptians to support the deposed head of state following his overthrow.
Asked if he would prohibit participation in the election, Qaradawi replied: "Of course".
He was speaking after taking part in a conference on Jerusalem organised in Doha by the International Union for Muslim Scholars.
Egypt's military-installed interim government has designated the Brotherhood a "terrorist organisation" and launched a brutal crackdown on Morsi's Islamist supporters since his ouster last July 3.
In Qaradawi's speech at the conference, he accused Israel of backing Sisi, saying that its former premier "Ehud Barak is urging support for Sisi".
"Israelis have been happy since he (Sisi) has been in power, (and) we have seen nothing but death and blood since his arrival," he said.
Qaradawi is himself wanted by Egypt's authorities and faces being tried in absentia.
Qatar had close ties with Egypt during Morsi's turbulent single year in power, but relations nose-dived after his overthrow.
The gas-rich Gulf state has given refuge to a number of Brotherhood leaders who fled the bloody crackdown that followed Morsi's ouster.
Egypt has called on Qatar to respect a 1998 Arab counter-terrorism treaty and hand over Qaradawi and other wanted Islamists.