The documents of the six defendants were referred to the Grand Mufti, who according to the Egyptian law must review all death sentences. His decision is, however, not binding.
The court said that the final verdict will be announced on June 18 after the mufti's response.
Once the final verdict is issued, the sentences can be appealed.
Morsi as well as other defendants are charged with leaking classified documents to Qatar and selling them to al-Jazeera channel.
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Other charges include leading and joining outlawed group Muslim Brotherhood, that aims at changing the country's regime by force, and attacking army and police posts and public property.
The Egyptian government has been cracking down on Muslim Brotherhood and its supporters since the ouster of Morsi, which left thousands in jail and hundreds facing trials on a variety of charges.
Morsi and Muslim Brotherhood supreme guide Mohamed Badie and 100 other leaders were sentenced in June to death for escaping from prison in 2011.
Their sentences are currently in appeal.