ALBANY — The state Board of Elections has filed an unprecedented lawsuit that could end up closing a gaping loophole that has allowed big donors to circumvent campaign-contribution limits for years.

The civil suit, filed last month in Albany Supreme Court, challenges contributions made through limited-liability companies to a Brooklyn Assembly candidate in an election last May.

“The public is entitled to know who is contributing to candidates and committees,” said Risa Sugarman, the board’s chief enforcement counsel.

Sugarman charged that candidate Shirley Patterson received donations from several entities owned by the same individuals that cumulatively exceeded the $4,100 contribution cap.

Patterson, who didn’t return calls, and her campaign treasurer face fines totaling more than $47,000.

Federal prosecutors spotlighted LLC contributions when they brought corruption charges against former Senate Majority Leader Dean Skelos.