CAIRO (AFP) - The authorities in Egypt arrested a 19-year-old son of ousted Islamist president Mohamed Mursi on Saturday, accusing him of possessing hashish cigarettes, a charge denied by his brother.

Security officials said police found two joints on Abdullah Mursi and a friend who were in a car parked by the roadside in Qalyubia province north of Cairo.

The two were arrested for questioning, they added.

Mursi's other son, Osama, dismissed the allegation.

He said Abdullah was stopped at a police checkpoint while on his way home.

"He has been arrested. They are fabricating the case. My brother doesn't even smoke," Osama, a lawyer, said.

"This is a clear attempt to defame the family of president Mohamed Mursi.

This incident is part of a series of violations committed by the state against us."

Mursi and his Muslim Brotherhood have been target of a relentless government crackdown since the Islamist was ousted last July after just a year in office.

Amnesty International says more than 1,400 people have been killed, mostly Morsi supporters, in street clashes since his ouster.

Mursi himself and several Brotherhood leaders have been put on trial.