Moscow: President Vladimir Putin has demoted the Kremlin's chief of staff in a dramatic shake-up of Russia's leadership.

Sergei Ivanov, a former KGB officer, was abruptly removed from the post and made special presidential envoy for conservation, environment and transport.

In a televised meeting on Friday, Mr Putin told him: "We have worked for many years together with great success." Mr Ivanov replied: "Thank you for your high assessment of my work over the past 17 years," referring to his service in government since Mr Putin first became prime minister in 1999.

Mr Ivanov added that his four years and eight months as head of the presidential administration made him the longest serving Kremlin chief of staff since the break-up of the Soviet Union. Mr Putin appointed Mr Ivanov's little known deputy, Anton Vaino, as his successor. The reasons for his removal are unclear. Russia's official explanation was that he asked to be moved because he had been too long in the role.