New Delhi, Sept. 29 -- By Nimesh Vora

MUMBAI, Sept 29 (Reuters) - The Reserve Bank of India's foreign exchange operations have soaked up an estimated $20 billion of excess rupee liquidity, two bankers said, with dollar-rupee swaps playing a prominent role in liquidity management.

The RBI has used a combination of dollar-rupee sell-buy swaps, spot dollar sales, bond sales and variable-rate reverse repos in recent weeks to drain excess liquidity from the banking system.

Those measures, along with tax outflows, have more than halved the banking system's liquidity surplus from a record 11.16 trillion rupees ($116.10 billion) in the first week of the month.

Economists have said the decline was evident in core liquidity, which strips out da...