Two Canadians released from an Egyptian prison more than a month after their arrest during violent protests have been prevented from leaving the country, their lawyer said on Monday.

Filmmaker John Greyson and emergency room doctor Tarek Loubani had been prevented from boading a flight at Cairo airport after their release on the weekend, said the lawyer.

"Their names were on a travel ban list," said Marwa Farouk.

"We've submitted a request to the state prosecutor to allow them to leave," the lawyer told AFP.

Egypt's state prosecutor can impose travel bans on suspects under investigation.

The pair, who were transiting in Egypt on their way to the neighbouring Palestinian Gaza Strip when arrested, have not been formally charged.

They were detained in Cairo on August 16 amid bloody clashes between security forces and Islamists that killed dozens of people

Canadian Prime Minister Stephen Harper had on Sunday welcomed their release from prison.

"We look forward to seeing these two Canadian citizens return home in the not-too-distant future," Harper told reporters.