Felix G. Arroyo, chief of health and human services for the city of Boston, was fired by Mayor Martin Walsh last Thursday after “a comprehensive internal investigation” into allegations that he harassed a woman who worked for him, according city officials. The administration is actively looking for his successor.

“The city has already started to search for candidates to fill the Chief of Health and Human Services position and we hope to announce an appointment soon,” Walsh spokeswoman Laura Oggeri said in an email Tuesday.

Arroyo had been on paid administrative leave since July 28.

A woman who worked for Arroyo, a former city councillor and 2013 mayoral candidate, at City Hall filed a complaint with Massachusetts Commission Against Discrimination (MCAD), alleging that he had repeatedly sexually harassed her since October 2015.

The MCAD complaint alleged sexual harassment, retaliation on the basis of her sex and gender, and a hostile workplace. Walsh, who is in the midst of a re-election campaign, is named in the complaint along with the City of Boston, Arroyo, and Arroyo’s chief of staff, Ilyitch Nahiely Tabora.

The woman said Arroyo made sexually inappropriate comments and “spanked” her buttocks, and also grabbed the back of her neck after she contacted human resources in July. She said that a subsequent transfer to another position was a demotion.

Arroyo has denied the charges through Colette Phillips, a Boston public relations specialist, who said in a statement, “We are disappointed in this decision. Felix is adamant that these allegations are baseless and retaliatory and will continue to fight to clear his name and is looking forward to fully cooperating with the MCAD.”

Police have reached out to the woman to see if she intends to file a criminal complaint.

Walsh said they made the determination to fire Arroyo after reviewing the report. “Any time that we have any type of allegations in the city of Boston where there’s somebody that feels threatened or concerned, we’re gonna do an investigation and we’re gonna take the proper action and that’s what we did in this case,” he told reporters after an event last week.

The mayor said the city is conducting “an extensive search” for a new chief of the health and human services department. “It’s a very important role in the city and certainly something that we don’t want to keep open too long,” he said.