Virginia's unemployment rate reached its highest level in four years last month, rising to 4.9 percent, the Virginia Employment Commission announced yesterday.

The news was particularly unpleasant in Northern Virginia, which the report showed has lost 12,400 jobs in the last 12 months. By contrast, the state as a whole still is gaining jobs.

The figures provide a prelude to the December unemployment statistics for the entire Washington metropolitan area scheduled to be released Friday. At last count, joblessness in the region was 3.8 percent.

The December unemployment rate in Northern Virginia alone, according to yesterday's figures, was 2.9 percent, the lowest of any of the state's five regions. The low rate -- measured by a survey of households -- seems at odds with the statistics on jobs from the employment commission's survey of employers, which indicates that Northern Virginia has lost more jobs in the last 12 months than any other part of the state.

William Mezger, a research economist with the employment commission, said the seeming discrepancy probably is caused by people who lost their jobs in Northern Virginia and then returned to their homes farther away, in such cities as Fredericksburg and Winchester. Thus, they are no longer measured in statistics about the Washington region collected through the household survey. Mezger said unemployment in some of the outlying areas, as measured by households, has nearly doubled.

Many of those jobs were in construction, where more than 20 percent of positions have been lost in Northern Virginia in the last year.

Moreover, Mezger said, the jobless rate in Northern Virginia has increased considerably from 1.7 percent a year ago, and the number of unemployed people has risen.

The rise in the state rate -- from 4.5 percent in November -- came about because of a weak Christmas season, more year-end furloughs than usual in manufacturing and regular winter cutbacks in some industries. The unemployment numbers -- which unlike the figures for the nation are not adjusted for seasonal variations -- tend to rise in winter months. The comparable national rate was 5.8 percent.

The employment commission said it expects the state rate to climb to 5.3 percent or 5.4 percent in January, typically the highest unemployment month of the year, and economists agreed the outlook was gloomy.

"I think that when we move into the spring, payroll jobs will decline somewhat statewide, pulled down by retail layoffs, further construction declines and a leveling in state and local government employment," said Roy L. Pearson, director of the bureau of business research at Williamsburg's College of William and Mary.

The war in the Persian Gulf has had a mixed effect on Virginia's economy, according to Mezger. On the one hand, unemployment has risen sharply in the Hampton Roads area as spending has stopped because sailors have been deployed to the Middle East and their families have cut back on spending. And the naval shipyard in Portsmouth has laid off workers because ships originally scheduled for rehabilitation and maintenance this winter have been sent to the gulf.

On the other hand, the ports have seen a noticeable pickup from the shipment of Christmas presents and military supplies to the gulf.