Jailed Egyptian-Palestinian freed after more than 2 years in prison
The source said that Shaath, the son of veteran Palestinian politician Nabil Shaath, "has been released by the prosecution". There were no further details.
His wife, French national Celine Lebrun, told AFP: "I heard about the decision but according to what I know he is not yet out."
She added that she would release a statement once he is confirmed to be free.
Lebrun was deported from Egypt shortly after her husband's arrest.
Earlier on Monday, prominent MP Mohamed Anwar Sadat had announced "an imminent decision to release" Shaath and deport him.
Shaath, 50, was a figure of the 2011 uprising in Egypt and the coordinator of the Egyptian chapter of the Boycott, Divestment and Sanctions movement against Israel.
He was arrested in July 2019 and faced charges of aiding a terrorist organisation.
In April 2020, he was placed on Egypt's terror list alongside 12 other people.
In December, five human rights groups called on French President Emmanuel Macron to pressure Egypt to release Shaath.
Macron had previously addressed his detention in a news conference in Paris with Egyptian President Abdel Fattah al-Sisi in December 2020.
Egypt's space for dissent has been severely restricted since Sisi took office in 2014.
Rights groups say Egypt is holding some 60,000 political prisoners, many facing brutal conditions and overcrowded cells.
Egypt ranks in the lowest group on the Global Public Policy Institute's Academic Freedom Index.
The decision to release Shaath comes almost a month after an Egyptian court freed researcher Patrick Zaki whose detention in 2020 sparked international condemnation.
Zaki was freed on December 7 but still faced charges of "spreading false news", "harming national security" and "incitement to overthrow the state", among others.
He had been referred to trial in September before an exceptional state security court for an article containing excerpts from his personal diary recounting the discrimination faced by the country's Coptic Christian minority.
Amnesty International previously said Zaki had allegedly been tortured while being interrogated by national security officers, including using electric shocks and beating.
Zaki's detention also strained ties with Italy where he had been studying.
In a 2019 interview with the show 60 Minutes on US broadcaster CBS, Sisi said there were no political prisoners in Egypt.
The former army chief became president in 2014 after leading the military ouster of president Mohamed Morsi a year earlier.