WASHINGTON — The National Transportation Safety Board called on the 12 states that have yet to pass laws requiring the mandatory use of automobile seat belts to do so quickly in the interest of saving thousands of lives.

In a letter to the governors of those states, the safety board said that a two-year study it conducted found that lap and shoulder belts offered substantial protection to those using them in a wide variety of auto crashes.

It noted government estimates that seat belts saved 19,361 lives from 1984 to 1989, with just 14,191 of those accidents occurring in states with mandatory seat-belt laws.

The states without such laws are Alabama, Delaware, Kentucky, Maine, Massachusetts, Nebraska, New Hampshire, North Dakota, Rhode Island, South Dakota, Vermont and West Virginia.