Former Fairfax delegate Wyatt B. Durrette, an undeclared Republican candidate for governor next year, has failed to file three required campaign finance reports to account for a $100,000 debt left over from his unsuccessful 1981 race for state attorney general.

Asked about the missing reports, which have gone unnoticed by the State Board of Elections, Durrette, now a Richmond attorney, said through a spokesman today that it was an oversight by his campaign and that an updated report probably will be filed next week.

Donald W. Lemons, a campaign official for Durrette's 1985 organization, said the $100,000 debt was forgiven in 1982 by six individuals who loaned Durrette amounts ranging from $10,000 to $20,000. "In fact, there is a modest surplus now," Lemons said.

One $20,000 loan was from Bruce Gottwald, president of the influential Ethyl Corporation and a leading money raiser for the state Republican Party.

Lemons said he learned of the unfiled reports only two weeks ago when a volunteer campaign worker raised the issue. "I'm quite sure it was an innocent oversight," he said.

In all, Durrette spent about $654,000 in his campaign.

The three campaign reports were due in May and November 1982 and November 1983, according to elections officials. Another annual report is due next month.

Under state law in force in 1982, campaign organizations must continue to file reports until a candidate accounts for all financial obligations incurred during a campaign.

Willful failure to file is a misdemeanor and carries a $100 fine, according to elections officials who said Durrette was unlikely to face any action since the board itself had not requested the late reports.

"You can't call it willful unless you know that candidates haven't filed after being reminded," said Audrey S. Piatt, a special assistant to the board.

Former Republican Attorney General J. Marshall Coleman of McLean, who lost a bid for governor in 1981 and is considering another try for that office next year, said today that the remaining $33,000 debt from his 1981 campaign would be paid off before next month's filing date.

Coleman ended his 1981 campaign with a debt of about $200,000.

In addition, several supporters forgave loans to the campaign, including Richmond investor Lawrence Lewis Jr., who contributed a total of $302,000 to Coleman's $2.9 million campaign.