CAIRO, Aug 3 (Reuters) - Hussein Salem, a businessman and ally of Egypt's deposed president Hosni Mubarak, and his family have given up 75 percent of their wealth in a deal that will allow them to return to Egypt without facing prosecution, his lawyer said.

Salem was arrested in 2011 under an international warrant in Spain, where he fled in the aftermath of the 18-day popular uprising that ended Mubarak's 30-year rule.

An Egyptian court sentenced him in absentia to seven years in jail and fines totalling more than $4 billion in 2011 after convicting him of money laundering and profiteering. He later faced further graft-related convictions but was cleared in 2014 of charges related to gas exports to Israel along with Mubarak and a former oil minister.

"I am very happy with the outcome of the case and feel that we can begin to move forward," says Mahmoud Kabish, a former dean of the Faculty of Law at Cairo University and Salem's lawyer.

Salem, who also holds Spanish citizenship, was a major shareholder in East Mediterranean Gas (EMG). Egyptian opposition groups had long complained that EMG was selling gas at preferential prices to Israel and other countries, depriving Egypt of potential revenues.

Egypt's Illicit Gains Authority recovered 5.3 billion Egyptian pounds ($596.85 million) in the reconciliation deal with the Salem family, according to state television.

Adel al-Saeed, a spokesman for the prosecutor's office, said the tycoon transferred 75 percent of his wealth to state ownership, including land, agriculture, and hotels.

Saeed said the deal guaranteed that Salem and his family, who also had extensive investments in Red Sea resorts, could return to Egypt without facing prosecution.

The deal is part of a wider reconciliation effort with wealthy businessmen who fled Egypt to avoid corruption charges after the uprising. ($1 = 8.8799 Egyptian pounds)

(Reporting by Mostafa Hashem; Additional Reporting and Writing by Lila Hassan; Editing by Alexandra Hudson) ((lila.hassan@thomsonreuters.com;))