DETROIT (Reuters) - Toyota Motor Corp plans to introduce a onboard communications and navigation system in the U.S. market this year that will compete with General Motors Corp's market-leading OnStar service.

Toyota's in-house developed service will be available on select models for both its mass-market Toyota and Lexus luxury brands, and will be offered to new customers for one year free of charge, the automaker said on Wednesday.

Toyota, No. 2 in U.S. auto sales behind GM, said that beginning in late summer, some Toyota and Lexus models would have factory-installed hardware for the system that can be activated upon subscriptions at dealerships.

Toyota will offer one-year trial subscription for new vehicle purchases.

The service, like GM's OnStar, is designed to provide drivers with emergency support in the event of an airbag deployment or an accident, through embedded cellular technology and a satellite-based navigation system.

The system-equipped vehicles also come with an SOS button, through which customers can communicate with emergency call centers for 24 hours a day.

In the event a vehicle is stolen, the service also assists in tracking the location of the stolen vehicle, Toyota said.