CAIRO — After years of the government’s promising to end Egypt’s state of emergency, Parliament on Tuesday approved a government request to extend for two years its right to arrest people without charge, detain prisoners indefinitely, limit freedom of expression and assembly, and maintain a special security court.

In an unusual case of public outreach by Egypt’s normally tight-lipped leaders, the government took pains to explain its decision and announced that the emergency law — in place continuously since President Anwar el-Sadat was assassinated in 1981 — would be used only in cases of terrorism and drug trafficking. Officials also said that some provisions of the law would be dropped.

But the concept of terrorism is so broad in Egyptian law and the language in the new measure so malleable, that the government decision was immediately criticized by human rights groups, political activists and independent human rights monitors, who say they expect little to change in a nation that routinely uses the heavy hand of the police and prisons to silence political opposition.

“Even the claim that emergency powers will now be limited to terrorism and drug trafficking cases only is false,” said Hossam Bahgat, executive director of the Egyptian Initiative for Personal Rights. “More dangerously, the culture of exceptionalism stays, and with it the message that security agencies are still above the law.”