Union activity at online retailer

Amazon.com

(AMZN) - Get Report

is at a standstill, say organizers, and it now appears increasingly unlikely that employees who lost their jobs will seek an investigation by the federal government into the allegation the company targeted workers for layoffs because of their union involvement.

In addition, most employees have signed separation agreements requiring them to give up their right to sue the company, according to workers.

"The union has kind of been put on the back burner," says Zach Works, a union representative who will keep his job in the customer service department at Amazon. "There's not much we can effectively do."

In February Amazon announced plans to lay off some 1,300 workers in a bid to slash cuts and move closer to profitability. Among the layoffs were about 350 workers at a Seattle customer service center, which was the center of nascent union activity at Amazon. Management had long sought to quell the union activity, and the layoffs sparked the claim by organizers that they were targeted because of their organizing efforts, a violation of federal labor law. The company says it opted to shutter the customer service center because running it was costly.

Laid-off employees have until about August -- six months from the announcement of the job cuts -- to file a complaint with the

National Labor Relations Board

seeking an investigation into whether the employees were unfairly targeted, says Marcus Courtney, co-founder of

WashTech

, a union of technology workers that has long sought to unionize the Amazon customer service workers. Courtney says "it is still a possibility" that such a claim will be filed.

However, it appears unlikely that a federal investigation into the allegations, which are very hard to prove, will ever occur, say workers.

Shortly after the layoffs, union organizers

won a minor victory when management ditched its gag order that would have barred employees who collect severance money from talking publicly about Amazon.