SAN FRANCISCO — Yahoo is planning a new round of layoffs, the first since Carol Bartz became chief executive in January, according to several people with knowledge of the situation.

The layoffs could affect several hundred employees and may be announced as early as Tuesday when Yahoo reports first-quarter financial results, said these people, who agreed to speak on condition of anonymity because the plan is confidential.

A Yahoo spokesman, Brad Williams, declined to comment, citing a company policy not to discuss rumors and speculation.

The cuts would be the third round of layoffs at Yahoo in little more than a year. The Internet company, which has been struggling for more than two years, laid off about 1,000 workers early in 2008. It cut 1,400 or so in the fourth quarter of last year, in continuing efforts to prune its sprawling online business and bring down expenses. It ended the year with 13,600 employees.

In recent years, Yahoo has seen its growth slow and has lost ground to Google in online search. Despite its huge online audience of roughly 500 million people worldwide, it also missed the opportunity to acquire fast growing social Web sites, like YouTube or Facebook, which have become a magnet, especially with younger users.

And its display advertising business, which was concentrated on high-priced ads, has been undercut by the proliferation of sites that offer marketers a way to reach audiences at lower prices. The company has suffered from a continuing exodus of executives and a series of revampings that have damaged employee morale.

Late last year, Yahoo was hit with the deepening recession, which took a further bite out of the company’s online advertising business.

“If you look at the changing economic environment and the changing leadership, it is not surprising that you would see further cuts at the company,” said Scott Kessler, a stock analyst with Standard & Poor’s.

Under Ms. Bartz, Yahoo has also been trying to sell some business units that it doesn’t consider core to its mission, including Hotjobs, the online recruiting service, according to several people familiar with the plans.

Ms. Bartz has been reviewing Yahoo’s businesses. In recent weeks, she renewed discussions with Microsoft, which attempted to buy Yahoo early last year, and later tried to acquire the company’s search business. The new round of talks center around a possible advertising partnership, not an outright acquisition or a sale of Yahoo’s search business, according to people familiar with the discussions.