MOSCOW — Aleksei A. Navalny, the Kremlin’s highest-profile domestic critic, was released from jail on Friday after 30 days and said that opposition to President Vladimir V. Putin and protests against the authorities would grow despite efforts to crack down on the opposition.

Mr. Navalny, who has tried to garner popular support by exposing corruption in Russia, spoke just after completing a sentence for encouraging a protest calling for free elections.

“Now we see that lies and fraud are not enough for themm” he said. “It’s not enough for them to ban candidates from an election. They deliberately want to arrest dozens and to beat up hundreds.”

“This shows that there is no support for this regime,” Mr. Navalny added. “They feel this and they are afraid.”