The union representing the janitors who clean Massachusetts Bay Transportation Authority stations is alleging unfair labor practices by two state contractors, in the wake of recent layoffs.

The federal complaints against S.J. Services and ABM Industries, filed with the National Labor Relations Board, allege that the companies did not negotiate in good faith with workers before the layoffs on Thursday. They follow weeks of protests from 32BJ Service Employees International Union District 615, the janitors’ union.

“These janitorial cuts have been forced down the throat of the janitors and the millions of T riders who expect and deserve clean and sanitary stations,’’ Roxana Rivera, vice president of the union, said in a statement.

Chas Strong, a spokesman with ABM, said the company worked closely with the union and had confidence “the current level of cleanliness will not be disrupted.’’

Before the layoffs, the contractors employed about 300 workers who clean the T stations. The contractors lost a total of 32 positions, according to the MBTA, though union officials said the companies told them cuts would affect closer to 70 positions. Others have been asked to accept fewer hours.

MBTA spokesman Joe Pesaturo noted that the contracts do not mandate how many janitors must be employed, but set requirements for how clean the stations must be.

“The MBTA will continue to hold its contractors to the highest standards so customers will be provided with a clean, comfortable, and reliable transit system,’’ he wrote.

During an annual Labor Day breakfast on Monday sponsored by the Greater Boston Labor Council, supporters are expected to rally to show solidarity with the janitors. Next week, representatives for the janitors will meet with Governor Charlie Baker’s chief of staff, Steven Kadish.

Nicole Dungca can be reached at nicole.dungca@globe.com.