Federal safety authorities have opened an investigation into what they termed a "high number" of rollover accidents involving Ford Bronco II sport utility vehicles.

The National Highway Traffic Safety Administration said the investigation covered about 590,000 Bronco II models built between 1984 and 1989.NHTSA spokesman Tim Hurd said he had no figures for roll-over deaths. But he said crash statistics showed the Bronco II "seems to have a high number of single vehicle rollovers involving fatalities."

Ford Motor Co. responded that the number of fatal accidents involving the Bronco II "is not significantly different" than for other sport utility models.

NHTSA spokesman Hurd said the investigation of the Bronco II stemmed from complaints by consumer groups that Suzuki Samurai vehicles were more likely to roll over than similar vehicles.

Last summer, Samurai sales took a nose-dive after the vehicle was rated "not acceptable" by Consumer Reports magazine, which found the vehicles rolled over during certain types of testing.

The NHTSA found the Sumurai did not have a propensity to roll-over but that the Bronco II did.