Indian Police Service officer Ranjit Sinha Monday took charge as the 25th director of the country's premier investigating agency - the CBI, officials said.

Sinha's appointment has been marred by a controversy with the opposition Bharatiya Janata Party questioning the manner in which the 1974 batch IPS officer was appointed by the Congress-led government.

Sinha succeeds Amar Pratap Singh who stepped down as director of the Central Bureau of Investigation (CBI) Nov 30 after completing his two-year tenure.