“We are an open society. People openly express their opinions. Lots of justified cricism is being voiced,” he told a foreign investor conference in Moscow.

“But you have to tread very carefully here. Changes are certainly needed and they will happen,” he said in his first major public speech since announcing a decision to run for president in March presidential polls late last month.

“But this will be an evolutionary path. We do not need great upheavals. We need a great Russia.”

On September 24, at a convention of the ruling United Russia party incumbent President Dmitry Medvedev, whom investors had seen as a more liberal figure, said he would step aside to allow his mentor, a former KGB officer, to return to the Kremlin.

The constitution allows Putin, who has been in power since 1999 as president and then prime minister, to remain head of state until 2024, with two more six-year terms at the Kremlin.

His critics are concerned that his comeback could plunge Russia into decline and stagnation, with many Russians comparing Putin to the much-ridiculed Soviet leader Leonid Brezhnev, whose 18-year rule helped trigger the collapse of the Soviet Union.