The European Central Bank will lend euro-area banks a record amount for three years in its latest attempt to keep credit flowing to the economy during the sovereign debt crisis.

The Frankfurt-based ECB awarded 489 billion euros ($645 billion) in 1,134-day loans today, the most ever in a single operation and more than economists' median estimate of 293 billion euros in a Bloomberg News survey. The ECB said 523 banks asked for the funds, which will be lent at the average of its benchmark interest rate — currently 1 percent — over the period of the loans. They start tomorrow.

“It was obviously an offer the banks could not refuse,” said Laurent Fransolet, head of fixed-income strategy at Barclays Capital in London. “It shows the ECB is not out of ammunition and it gives banks security on liquidity for a few years. On the other hand it means banks will rely on the ECB for longer.”