PONTIAC, Mich. (AP) _ The $10.1 million an insurance company will dole out because of damage to the Pontiac Silverdome may have been a major factor in its decision to discontinue the dome's policy in June, stadium officials say.

''That was the straw that broke the camel's back,'' said James Clarkson, chairman of the Pontiac Stadium Authority. ''I can't fault them after they realized that this kind of event meant the loss of the entire roof.''

Affiliated F.M. Insurance Co. of Johnston, R.I., declined to give a reason for the cancellation to either the Detroit Free Press or The Detroit News. Stadium officials said Thursday that they expect to receive a $3 million check from the company Friday as a first installment toward the settlement.

AFM will have to pay $8 million for repairs on the 10-acre roof, $600,000 to replace damaged concrete and seats, and at least $1.5 million for business interruption, officials said.

Clarkson said the company sent the authority a 90-notice of cancellation about two weeks after the dome's roof caved in during a snow storm March 4.

Part of the stadium roof collapsed under the weight of snow and ice, and high winds tore out most of the remaning panels after the storm.

The Silverdome's policy expires June 16, just 54 days before its scheduled reopening on Aug. 9 - the first home game of the Detroit Lions' National Football League exhibition season.

But the dome cannot reopen without insurance, Clarkson said. He said insurance aides ''have been shopping around like crazy'' with no takers, Clarkson said. He said neither the stadium authority nor the city is capable of insuring the Silverdome independently.

''We expect to have a policy by the first week of June,'' said Richard Huttenlocher, a Pontiac insurance agent who arranged coverage for the 80,638- seat Silverdome when it opened 10 years ago.