CAIRO — Egyptian rights advocates and nonprofit groups are bracing for a crackdown and fleeing the country, but the official who oversees them says there is nothing to fear.

It depends in large part on how prosecutors will apply a sweeping law decreed by the new military-backed president, Abdel Fattah el-Sisi, as a tool to fight terrorism. Rights activists say the new rule is a sign that the crackdown on dissent following last year’s military takeover is making Egypt a stricter and more repressive police state than at any other time in the last 35 years.

“Everyone in civil society is panicking,” said Ragia Omran, a prominent human rights lawyer.

The new law imposes a potential life sentence for the crime of intending to “harm the national interest,” “compromise national unity” or “breach security or public peace,” if it involves receiving money from abroad. Foreign funding is how virtually every credible human rights group here has subsisted for decades because of the legal and practical obstacles to domestic fund-raising under Egypt’s authoritarian governments.

In an interview this week, the official in charge of nonprofit groups, Ghada Waly, the minister of social solidarity, said the judicial authorities had assured her that the law would apply only to those using foreign funding “for terrorist attacks and terrorist activities and destabilizing activities.”