Rights groups in Egypt are bracing for a possible crackdown as a government-issued ultimatum expires.

The government has ordered non-governmental organizations to register by Monday under a law issued by Egypt's longtime dictator Hosni Mubarak — which gives the state sweeping authority over their activities and financing — or face possible prosecution.

The government claims the ultimatum is a straightforward issue of law enforcement, but many rights groups view it as a direct threat amid a widespread crackdown on government critics.

In a statement Monday, the Egyptian Organization for Human Rights — one of the oldest rights groups in Egypt — called on the government to extend the registration deadline so the law could be revised to comply with the constitution.