Sources said the central bank is likely to target the trading banks which include a large number of foreign banks, a few private sector banks and a nationalised bank. "The trading banks will be targeted as generally they indulge in this (speculation)," a source said.

"It's going to be a routine inspection. In fact, periodic inspections have been on since June 15 when RBI issued a directive warning importers not to hedge more than their requirements," a source said. Banks were directed by the RBI to advise importers accordingly. However, the central bank has been alarmed by the sudden spurt in corporate demand for the greenback witnessed between August 3 and August 14.

The RBI inspectors from the exchange control departments will go through the books of the banks to see whether any speculation has taken place. On Monday, it sent a letter seeking details about the transactions entered into by corporates with banks. "They just want to ensure the names of the corporates if the banks are not forthcoming. The rupee touched the lifetime low of Rs 43.35 on Tuesday on the back of heavy corporate buying (it dipped further on Tuesday).

The RBI has told banks to ensure that they conduct the forward leg of the transaction first and then undertake the spot transaction. "The RBI has been asking questions as to why only spot transactions are taking place and no forward dealings. The forward leg has often been cancelled on account of profit booking by banks. The RBI wants to ensure that this does not take place," a dealer at a foreign bank said.