CAIRO—Egypt's public prosecutor issued arrest warrants for five prominent pro-democracy activists on suspicion of inciting violence during weekend rioting, raising fears of a crackdown against opponents of the politically dominant Muslim Brotherhood.

The warrants on Monday came one day after Brotherhood-backed President Mohammed Morsi, in a stern televised address, threatened to "do what is necessary to protect this nation." Rioting in front of the Brotherhood's headquarters on Friday left at least 200 people injured.

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