WASHINGTON — The Justice Department threw its support on Friday behind housing advocates who accuse Facebook of violating fair-housing laws.

In a so-called statement of interest, the department suggested that Facebook could be held liable if housing providers like real estate developers and landlords used the site’s targeting tools to discriminate against prospective renters and buyers in advertising their properties.

Such tools limit who can see ads based on factors like sex, religion and nationality, and advertising restricted along those lines violates the Fair Housing Act.

Statements of interest are typically reserved for cases that directly affect the federal government’s interests, like national security and diplomacy.