"Independent newspapers have gained some space over the past few years, but Mubarak is trying to roll that back," he said.
One of the newspapers' editors faces charges in a separate lawsuit for spreading rumours that the 79-year-old Mubarak is in poor health.
Another opposition newspaper editor and two journalists were also sentenced recently to two years in prison for allegedly publishing false news about the country's judiciary.
Editors jailed
In September, an Egyptian court sentenced four newspaper editors to one year in prison for defaming President Hosni Mubarak and his son, drawing condemnation from human rights groups.
Last month, the White House said it was concerned about what it called setbacks on press freedom and civil society in Egypt.
The Egyptian government dismissed the criticism as unacceptable interference in internal affairs.
Ahmed Enany, board member of the Egyptian Press Syndicate, said: "We are calling on the government to implement the promise of president Mubarak to end the imprisonment of journalists.
"The government should not scare journalists and should let them work in a free environment," he said.