The group of economic indicators that often signal changes in the economy declined for the 10th straight month in February, suggesting that any recovery from the recession may still be some months away, the Commerce Department reported yesterday.

The decline was only 0.3 percent last month in the index of leading indicators, but a drop in January, originally put at 0.6 percent, was revised to show a fall twice as large. Commerce's chief economist, Robert Ortner, said, "There is no suggestion the recession will have ended in March or April."

Commerce Secretary Malcolm Baldrige said the January figure was revised downward primarily because of information about business inventories on hand and on order, an indicator not available at the time of the preliminary report. The inventory figures "will probably have the same effect on the February index," he said.

"When the recovery takes hold--which I think will be in a few months--it will be on a long-term, steady course," Baldrige told a group of utility executives, implying a recovery this summer, not this spring.

However, Treasury Secretary Donald T. Regan stuck with the administration's official forecast of a spring recovery in testimony to the House Banking Committee. "We believe the second quarter will be a plus quarter" but with real output rising at less than a 1 percent annual rate followed by strong growth at a 4 1/2 percent to 5 percent rate in the third quarter, he said.

Regan predicted that short-term interest rates "will come down sharply" if Congress would adopt President Reagan's fiscal 1983 budget, which calls for a deficit of about $96 billion.

Pressed by committee Chairman Fernand J. St Germain (D-R.I.) to be more specific, Regan said: "If our program is enacted, then there will be a 10 1/2 percent T-bill rate later this year." At Monday's weekly auction rates on 13-week Treasury bills rose nearly a percentage point to 13.4 percent.

"The fear of high deficits is what has high money rates staying up there," Regan said. "Right now, we have a psychological block in people's minds that these deficits . . . will be triple digits, $120 billion to $150 billion each year and rising over the next two to three to four years and that will cause severe inflation later."

Interest rates will remain high until the administration and Congress provide convincing evidence of spending cuts that will keep the deficit under $100 billion a year, he said. If financial markets "are convinced that we are going to work seriously to get deficits down, interest rates will break . . . and as they break, they will feed upon themselves," Regan argued.

According to reestimates of the Reagan budget by the Congressional Budget Office, the deficit for 1983 would still be more than $120 billion even if all of the proposed spending cuts and tax increases were passed by Congress. "Nobody on earth thinks this if adopted, will have a deficit of only $96.5 billion," declared Rep. Charles E. Schumer, (D-N.Y.).

A number of private economists remain divided as to when they expect the economy to reach a turning point and just how strong they expect the recovery to be.

"The evidence of the last four weeks suggests that the recession has not yet run its course, but that the inflation improvement is even better than expected," Otto Eckstein of Data Resources Inc., told clients of his economic consulting firm. "While the mid-year tax cuts are still expected to fuel a moderate recovery, the financial risks continue to be serious."

Eckstein noted that initial claims for unemployment insurance have jumped back to levels not far below their recession peaks, and that domestic auto sales in the first 20 days of March were running at an annual rate of only 5.7 million units, about 14 percent below the February sales pace. Those facts, and other evidence, he said, do not point to an immediate upswing.