The nation's unemployment rate remained at a seasonally adjusted 10.4 percent last month as some of the gains recorded in January in the number of payroll jobs and hours worked were erased, the Labor Department reported yesterday.

Analysts interpreted the figures cautiously, saying that problems with seasonal adjustment and unusual weather patterns in many parts of the country had affected the totals. Nevertheless, the numbers seemed to indicate that the recovery from the recession might not be taking off as fast as some people had hoped, they said.

The number of unemployed workers rose slightly to 11.49 million, while the size of the civilian labor force was virtually unchanged, the department said. In January, the unemployment rate had dropped to 10.4 percent from 10.8 percent in December, primarily as a result of an unusually large drop of 581,000 in the labor force and an equally large decline in the number of people looking for jobs but unable to find them. Civilian employment fell by 40,000 to 99.06 million.

The report added to the pressure on the Senate for quick passage of a $4.9 billion job-creation bill enacted Thursday by the House of Representatives. The AFL-CIO, for instance, said the new figures "show clearly that the chance at a job has not improved for American workers" and that governmental action "in a bigger and faster dose than the beginning step passed by the House" is needed to spur job creation.

At the White House, spokesman Peter Roussel reacted to the report by saying, "The overall thrust of the economy is good . . . Despite some ups and downs on the road to recovery, we believe the administration has laid a solid foundation for permanent reduction in unemployment and are confident this will occur."

There were two modest signs of an improvement in labor markets in the February report. First, the number of unemployed who have been without work for 15 weeks or more has fallen by more than 100,000 over the last two months to 4.62 million. Second, the number of persons working part time who usually work full time is down to 2.097 million from 2.38 million last October.

If persons in the armed services are included in both the labor force and employment levels, the unemployment rate in February was 10.2 percent, also unchanged from that measure's January level and down from 10.7 percent in December.

The unemployment rate for adult men, which had fallen from 10.1 percent in December to 9.6 percent in January, climbed back to 9.9 percent. The rate for adult women declined from 9 percent to 8.9 percent last month. It had been 9.2 percent in December. Unemployment among teen-agers was 22.2 percent, down from 24 1/2 percent in December and 22.7 percent in January.

For whites, unemployment rose from 9.1 percent to 9.2 percent, while that for blacks fell from 20.8 percent to 19.7 percent. The rate for persons of Hispanic origin rose from 15 1/2 percent to 15.8 percent.

On the basis of its monthly survey of employers, the department said the length of the average workweek for production and nonsupervisory workers other than on farms fell from 35.1 hours in January to 34.4 hours last month, a level 0.4 hours lower than in December.

The drop in the workweek was even steeper in manufacturing, from 39.8 hours to 38.9 hours, putting it back to its December level. The January increase accounted for more than one-fifth of the very large 3.6 percent rise in the index of leading indicators reported earlier this week, and now it has been reversed.

Employers also reported a decline of 180,000 in the number of employes on their payrolls last month after an increase of 330,000 in January.

Similarly, part of the January increase in retailing employment was lost in February. If December and January figures are averaged to eliminate seasonal-adjustment problems, as some analysts suggest, then employment in wholesale and retail trade changed little over the last five months.

The declines in the length of the workweek and in payroll employment pushed down the department's index of aggregate weekly hours by a substantial 2.3 percent. A decline of 1.8 percent in manufacturing could well mean that industrial production fell in February after two monthly gains in a row, analysts said.

Janet L. Norwood, commissioner of labor statistics, told the Joint Economic Committee it is likely that there was no further decline in civilian unemployment because businesses were assessing prospects for an economic turnaround before recalling laid-off workers.

Other Labor Department analysts also cautioned that further declines in the unemployment rate could come slowly if the prospect for additional jobs causes discouraged workers to re-enter the labor force. In the fourth quarter of last year, 1.85 million persons were officially reported as not seeking work because they thought no jobs were available for them.