NEW YORK (Bloomberg) — The Federal Reserve left its main interest rate at 2 percent, rebuffing calls by some investors for an immediate cut after Lehman Brothers Holdings Inc.'s bankruptcy shook markets worldwide.

The Fed did signal it will consider a reduction in the future by acknowledging in its statement that strains in financial markets are increasing. The central bank also said that employment is weakening and export growth is slowing, and dropped a reference to elevated inflation expectations.

"Tight credit conditions, the ongoing housing contraction, and some slowing in export growth are likely to weigh on economic growth over the next few quarters," the Federal Open Market Committee said after meeting in Washington.

Chairman Ben S. Bernanke is trying to draw a line between interest rates, which will be set based on its assessment of the broader economy, and emergency operations designed to combat financial turmoil. Less than 48 hours before yesterday's decision, the Fed expanded its lending to securities firms in the wake of Lehman's failure, including accepting equities as collateral for the first time.

Stocks initially fell after yesterday's decision, then rallied after a report that the central bank is considering a loan to American International Group Inc. That would be a shift from yesterday, when officials were inclined against providing funds.

"That continues the theme that the Fed is using targeted liquidity to be directed at the problems of Wall Street rather than the fed funds rate," said James O'Sullivan, a senior economist at UBS Securities LLC in Stamford, Connecticut. "Ultimately, they may have to move as well on the funds rate."

The decision was unanimous, the first such agreement in a year.

New York Fed President Timothy Geithner didn't come to Washington for the meeting, staying in New York, where talks continue at his bank on the crisis at AIG, which has slid 78 percent in the past week.

The Fed is considering a "loan package" to AIG, a person familiar with the negotiations said. Two people familiar with the situation yesterday said the New York-based insurer was seeking $70 billion to $75 billion in loans arranged by private banks.

Bernanke and Treasury Secretary Henry Paulson refused to offer federal aid to Lehman after its stock plunged last week, pushing the 158-year-old company into bankruptcy early yesterday.

Merrill Lynch & Co. became engulfed by the turmoil, agreeing to a quick merger with Bank of America Corp. this week, while insurer AIG struggled to stave off collapse after its credit ratings were cut.

The rout sparked by the collapse of the US subprime mortgage market has cost financial institutions worldwide $515 billion in writedowns and losses since the start of 2007. Firms have raised $362 billion of capital in response.

The New York Fed injected $70 billion of temporary reserves into the banking system today and $70 billion yesterday, the most since the September 2001 terrorist attacks. The central bank has also provided billions of dollars through direct loans of cash and Treasuries, and on September 14 widened the collateral accepted for loans to securities firms to include equities.

Still, banks are driving up short-term lending rates on concern AIG will follow Lehman into bankruptcy and leave financial institutions with losses on $441 billion of credit derivatives issued by the biggest US insurer. Central banks around the world pumped more than $210 billion into the financial system as they sought to alleviate the credit-market seizure.

Lehman's bankruptcy filing came amid signs that losses at financial institutions are impeding US economic growth.

The economy will slow to a 1.2 percent annual growth rate, or less than half the prior quarter's pace, as consumer spending, the biggest part of the economy, stalls this quarter, according to a Bloomberg survey.