The Reserve Bank of India's unexpected purchase of government bonds pushed down bond yields on Monday and raised bets for a cut in interest rates in February, investors said.

MUMBAI, Jan 27 (Reuters) - Indian government bond yields plunged at a start of a busy week, with the 10-year plummeting to a three-year low, as surprise bond purchases by the central bank boosted investor sentiment.

The Reserve Bank of India's unexpected purchase of government bonds pushed down bond yields on Monday and raised bets for a cut in interest rates in February, investors said.