At 11:12 a.m. (0542 GMT), the partially convertible rupee was at 51.60/61 per dollar, off its low of 51.7950 -- its weakest since March 12, 2009. At the day's low, the rupee was down 0.9 percent on the day.
"The quantum has not been too high today, but they (RBI) likely sold starting 51.79 and up to 51.69 levels," a senior dealer with a state-run bank said.
The central bank has always maintained that it does not protect any particular level on the rupee and would only intervene to iron out excessive volatility.
India's central bank intervened in the foreign exchange market in September, after following a hands-off approach for nine straight months, as the unit fell to its lowest level in more than two years, its monthly bulletin showed earlier this month.
The central bank releases intervention data with a two-month lag.