DETROIT ? General Motors Corp. will begin selling 15-passenger vans next month with standard stabilizing equipment, which the automaker says will increase the safety of a vehicle that the federal government contends has a significant rollover risk.

Meanwhile, Ford Motor Co., which also makes 15-passenger vans, said it would begin affixing rollover-warning labels on new models of the van, similar to warnings on the company’s sport utility vehicles.

Ford said it also has strengthened the safety language in the vans’ owners manuals, alerting drivers to the higher center of gravity and warning against abrupt maneuvers.

GM, the world’s largest automaker, said in May it would install the stability enhancement systems as standard equipment in GMC Savana and Chevrolet Express vans beginning with 2004 models.

Last year, the government renewed a safety warning for 15-passenger vans, which often are used by churches, sports teams and other groups. About 500,000 of the vans are in use on U.S. highways.

The National Highway Traffic Safety Administration has said the vans have a dramatically higher risk of rollovers when fully loaded and should be operated only by experienced drivers. With 10 or more passengers, the vans have a rollover rate that’s three times higher than when they have fewer passengers, according to the Transportation Department.