A Roman Catholic priest serving several midcoast churches but who has worked throughout Maine is on temporary administrative leave while the diocese investigates a decades-old abuse allegation, officials said Monday.

According to the Roman Catholic Diocese of Portland, the Rev. Robert Vaillancourt has been accused of sexually abusing an underage girl in the 1980s. He has been placed on administrative leave while the diocese’s Office of Professional Responsibility conducts an internal investigation, consistent with the diocese’s protocol for such allegations.

Vaillancourt currently serves as pastor of St. Brendan the Navigator Parish, which is composed of Our Lady of Good Hope Church in Camden, St. Bernard Church in Rockland, St. Francis of Assisi Church in Belfast, and St. Mary of the Isles Churches on Islesboro, Vinalhaven and North Haven. He was also recently appointed as hospital chaplain of Maine Medical Center in Portland.

“Fr. Vaillancourt has denied any wrongdoing and indicated that he will cooperate with any investigation into the matter,” the diocese said in a statement. “The temporary administrative leave is not a presumption of guilt or a result of suspected wrongdoing, but is the protocol followed by the diocese. It is for the purpose of preserving the integrity of the process. Public authorities have also been notified of the allegation.”

The diocese did not disclose where Vaillancourt was ministering at the time of the alleged abuse but said unnamed “public authorities” have been notified about the allegation. A spokesman for the diocese did not respond Monday to a request for more information.

A Lewiston native, Vaillancourt has served in various capacities within churches and programs throughout the state, including as the director of the diocese’s youth ministry program in the late 1980s.

After his ordination in 1982, Vaillancourt was assigned as associate pastor of St. Andre’s Parish in Biddeford before moving on to St. Thomas Aquinas in Madawaska, where, in addition to serving as associate pastor, he was director of the Christian Life Center in Upper Frenchville, according to biographical information from the diocese.

In 1988, Vaillancourt took over the diocese’s youth ministry program before joining St. Peter Parish in East Millinocket three years later. Since then, Vaillancourt has served as pastor of parishes in Old Town, Bridgton, Fryeburg, Madawaska, Hampden, Winterport, Rumford and Bethel, according to the diocese.

He has also held various other jobs in the diocese, serving as director of the Office of Vocations for a time and as temporary administrator for St. John Vianney Parish in Fort Kent during an investigation into allegations of embezzlement against that parish’s priest. The Maine Attorney General’s Office did not charge that priest, due to lack of evidence.

Any findings from the internal investigation will be presented to the Roman Catholic Diocese of Portland’s Review Board, which was created in 2003 in response to allegations around the country of Roman Catholic clergy sexually abusing minors. The board, which includes individuals with expertise in psychiatry and law enforcement, will then make a recommendation to Bishop Robert Deeley.