DETROIT - Borrowers should accept a new world of tighter, more expensive credit as financial institutions recover from months of bad loans, failed banks and foreclosed homes, Citigroup Inc.'s chief executive said Monday.

During the past few years, "U.S. consumption and credit creation were the two main drivers of growth," Vikram Pandit told a conference of business, economic and government leaders in downtown Detroit. "The world needs new drivers of growth , and a new business model."

Pandit's speech closed the first day of the three-day National Summit, which is expected to draw about 3,000 attendees to Detroit over three days. The goal of the summit is to craft a plan to keep the U.S. competitive in manufacturing, energy, technology and the environment.

He anticipates less credit that is more costly even as financial markets show signs of recovery. He also expects more corporate restructurings across different industries.

Citigroup has been among the most troubled banks throughout the crisis, receiving $45 billion in federal funds. Last month, the government determined that it would need to raise an additional $5.5 billion as a buffer against future losses.

Investors have criticized its board and management for allowing the bank to make big investments in the risky housing market , actions that led to Citigroup reporting billions in losses.

Pandit acknowledged Citigroup has "received much help along the way" and praised "strong government action" for starting to turn things around in the sector. But he said the company has taken many steps to restructure its business, including cutting its expenses by 25 percent and work force by about 20 percent, and lessening its dependence on credit and consumption.

He said some of the credit squeeze within the overall market is due to the "shadow banking system," largely unregulated finance companies that took wholesale funding and packaged it into student loans, credit cards and home mortgages. That system is responsible for nearly half all credit creation during the past five years, he said, and created a "credit gap" as those markets contracted.

Pandit said one new growth driver for U.S. financial markets is Asia, whose sustained growth requires a shift to domestic consumption.

"It creates tremendous export markets for American countries," he said. "We need unfettered access to these consumers and these markets."

Despite the challenges, Pandit said past U.S. economic downturns have created "breakthroughs" in new technologies and innovations, as well as venture capitalists who make investments.

"As we debate policies, we must take care that this model of growth is preserved," he said. "It is America's magic formula, but it is no longer America's secret."