The District government agreed yesterday to pay $1.45 million to a city teen-ager paralyzed in a high school football accident, as part of an agreement that appears to be one of the largest settlements ever paid by the city to an individual.

Mario Andretti Roberts had sued the city after his neck was broken and his spinal cord was severed in an October 1985 junior varsity football game at Dunbar Senior High School.

Roberts, the starting quarterback for Dunbar at the time, claimed in his suit that Dunbar coaches had failed to train him how to tackle properly to minimize the risk of injury.

After the accident, District school officials began a review of the school system's athletic rules and procedures; they are now considering expanding the requirements for and training of coaches.

Under the settlement announced yesterday to D.C. Superior Court Judge Gladys Kessler, the District did not accept responsibility for the accident. District lawyers had argued that football is an injury-prone sport and that serious injuries could and do occur no matter how well-trained a player might be.

Roberts, who was 16 when the accident occurred, was paralyzed from his chest to his feet when he attempted to tackle an opponent who had intercepted a pass and his opponent's helmet hit him under the chin.

Roberts' lawyer, Milton Heller, argued that Roberts' failure to move his head to one side during the tackle caused the injuries and was a direct result of inadequate training. Heller said Roberts received two days of training in proper tackling procedures; one week of training is suggested by most national high school athletic associations.

Heller argued during the litigation that the District was negligent because Dunbar did not have an adequate number of coaches and equipment to support well-trained varsity and junior varsity teams. Dunbar did not have a junior varsity football team this past year.

Heller said he was told by city attorneys that the highest previous settlement paid to an individual by the District was about $900,000. City attorneys could not be reached for confirmation.

School spokeswoman Janice Cromer said yesterday that the school system was reviewing its athletic policy and was particularly looking into "more training for coaches and expanding our requirements."

Cromer said, however, that "any corrective actions are not an admission of liability."

Since the late 1970s, the number of crippling football injuries has decreased significantly as more high school athletic associations have issued preseason training guidelines. Heller said his research showed that the the numbers of these kinds of injuries have dropped from about 45 a year to less than 10 a year currently.

"The significance of this case is that you just shouldn't field a team unless all the boys get the conditioning and training that is required," said Heller. "That's the bottom line."

Heller said Roberts is receiving special conditioning "to be more independent" and plans to finish high school and go on to college.

In an interview a year ago, Roberts told a Washington Post columnist that he became so depressed after his injury that he contemplated suicide but that he had put those thoughts behind him.

"You can do a lot more than you think if you really try," Roberts said then as he raised his arms over his head and then returned them to his side.

"It may not seem like much. But for me, the more I accomplish, the more I want to try."