Egypt's public prosecutor ordered on Friday the release of Saad El-Katatni, head of the Muslim Brotherhood's Freedom and Justice Party (FJP), and Brotherhood deputy leader Rashad Bayoumi pending investigations.
Both men were arrested on Thursday, one day after the Egyptian army toppled President Mohamed Morsi, who hails from the Brotherhood. They were later sent to Tora prison in Southern Cairo.
On Friday morning, Brotherhood lawyer Abdel-Moneim Abdel-Maqsoud was also detained after going to the prison to defend the two leaders. All three were interrogated on Friday at 6 pm.
Last Thursday, Prosecutor Tharwat Gamad ordered that investigations begin next week into Morsi and nine leading members of the Brotherhood.
Morsi, who took office last June after winning Egypt's first post-Mubarak democratic elections, was forced out of office on Wednesday by military chief Abdel-Fattah El-Sisi, in response to four days of nationwide mass protests that demanded early presidential elections.