Erdogan, a longtime supporter of Egypt's outlawed Muslim Brotherhood which was removed from power by the army last year, called President Abdel Fattah al-Sisi an "illegitimate tyrant", according to media reports.
The prime minister also slammed Egypt's efforts to mediate a ceasefire to end the conflict in Gaza between Israel and Islamist Hamas, which has rejected the truce proposal.
Erdogan is a vocal supporter of Hamas, which Egypt sees as a security threat because it is an offshoot of the Muslim Brotherhood.
He has ratcheted up his rhetoric against Israel and its allies in recent days, accusing the Jewish State of "surpassing Hitler in barbarism," and criticizing the US and the rest of the Muslim world for failing to intervene.
It is not the first time Turkey's premier has lashed out at Sisi, having previously accused him of toppling Egypt's Islamist president, Mohamed Mursi, in a "military coup".
Late last year, Egypt expelled the Turkish ambassador to Cairo, accusing him of undermining the country. Ankara responded by declaring the Egyptian ambassador to Cairo persona non grata.
Erdogan is hoping to become Turkey's first directly elected president in polls due on Aug. 10. Anti-Israel and pro-Muslim Brotherhood feeling is rife amongst the largely Sunni conservative voter base he is relying on to give him victory. REUTERS