Boosted by the sharpest food price rise in six months, consumer prices rose 0.3 percent in February, the Labor Department reported yesterday.

The February increase in the Consumer Price Index followed a 0.2 percent rise in January, the department reported. Although food prices rose 0.5 percent last month, motor fuels prices dropped 2.6 percent. Gasoline prices are now 17.1 percent below their peak level reached in March 1981.

The February increase leaves inflation for the last 12 months at a 3.5 percent rate, below the 4 percent pace for 1984.

In a separate report, the Commerce Department said new factory orders for durable goods dropped 0.2 percent in February, after an increase of 3.2 percent in January.

However, new orders for capital goods excluding defense, considered a gauge of future plant and equipment expenditures, increased 29.6 percent in February following a 13.1 percent decline the previous month. This gauge had been weak for most of the last eight months, suggesting that business investment would drop sharply. Economists said yesterday the rebound, while not signalling a trend, provides hope of increased business expansion.

The major reason for the decline in factory orders was a 48.5 percent decline in orders for defense capital goods, generally a very volatile statistic, economists said. Without the defense component, new factory orders for durable goods overall rose 4.7 percent in February.

At the White House, spokesman Larry Speakes welcomed the economic news.

He said that "inflation at the consumer level remains well contained."

The CPI last month stood at 317.4, which means that goods which cost $10 in 1967 cost $31.74 in February. Another index, used for indexing Social Security, some other federal payments and some collective bargaining agreements, was 313.9 last month.

The consumer price report came just one day after another government report indicated that a surge of imports is displacing domestic production and keeping economic growth at a low 2.1 percent rate in the first quarter.

The slow growth of the economy and the increase in imports, while upsetting to domestic manufacturers, are two of the major reasons for the moderate inflation picture, economists said.

Slower growth prevents shortages and bottlenecks in production that often lead to price hikes. In addition, the influx of imports that are cheaper than domestic goods not only keeps prices low, but encourages price competition between foreign firms and U.S. businesses.

"Overall, the inflation rate remains relatively stable, although there is some concern over the upticks in bread and butter items" such as food, housing and apparel, said Allen Sinai, chief economist for Shearson Lehman Brothers Inc.

Last month the costs of services rose 0.4 percent, a 4.9 percent annual rate, Sinai said. Goods prices rose 0.3 percent, a 3.4 percent annual rate, he noted.

Food and beverage prices rose 0.5 percent in February. The cost of foods purchased at grocery stores increased 0.6 percent, following a 0.3 percent rise in January.

The food price increases reflected shortages in supplies of most fresh fruits and vegetables due largely to the adverse January weather, the Labor Department said.

However, the price index for meats, poultry, fish and eggs declined 0.2 percent following a 0.3 percent drop in January, Labor said. The cost of beef, veal, lamb, fish and seafood dropped, more than offsetting rises in the price of pork, poultry and eggs. Moderate increases were reported for cereal and bakery goods, dairy products and other foods eaten at home.

Restaurant prices increased 0.4 percent.

Housing costs increased 0.4 percent, following a 0.1 percent rise in January. Costs for shelter and furniture both rose 0.6 percent, providing the largest boost for housing costs, the Labor Department said.

The prices of new and used cars rose 0.8 percent and 1.9 percent, respectively. Automobile finance charges declined for the third consecutive month in February, dropping 0.9 percent.

The index for public transportation was unchanged due to a decline in intercity bus fares, which offset higher taxi costs.

Clothing prices rose 1.0 percent because seasonal sales ended earlier than in previous years, Labor said.

Medical care costs increased 0.4 percent, following a 0.3 percent rise in January.