Amazon has fired two employees with ties to the grassroots union that led the first successful US organising effort in the retail giant’s history.

The company confirmed it had fired Michal Cusick, known as Mat, and Tristan Dutchin of the Amazon Labour Union on Staten Island, New York.

The tech firm claimed the “cases are unrelated to each other and unrelated to whether these individuals support any particular cause or group”.

Mr Cusick, who worked at a nearby Amazon warehouse to the one that voted to unionise last month, said he was fired due to Covid-related leave.

He said he had been informed by an agent from the company’s employee resource centre that he was allowed to go on leave until April 29 but was later fired because leave period extended only until April 26.

“They now say after the fact, after they terminated me, that the Covid leave actually only extended to the 26th,” said Mr Cusick, an organiser who works as the union’s communications lead. “That discrepancy is how they fired me.”

He said he was locked out of Amazon’s internal employee system on May 2 without any notice. The following day, he said he called the employee resource centre and was told about his termination.

In a letter sent on May 4, the company told him he had been fired for “voluntary resignation due to job abandonment”.

Amazon spokesperson Kelly Nantel said in a statement on Tuesday that Mr Cusick had “failed to show up for work since an approved leave ended in late April, despite our team reaching out to him and even extending his leave”.

“While we normally wouldn’t discuss personnel issues, we think it’s important to clear up some misinformation here,” she added.

On Monday, Mr Cusick had told the AP his firing may have been an arbitrary decision by Amazon’s automated human resources system, which has been a subject of scrutiny in the past.

“If they do not reverse what is a fairly obvious miscarriage of justice here, my presumption is that they are not doing it because they know that I am an Amazon organiser,” he said.

Ms Nantel said Mr Dutchin, another organiser who worked at the facility that voted to unionise, had been fired because he failed to meet productivity goals.

She said he “had been given five warnings since last summer for performance issues and was consistently performing in the bottom 3% compared to his peers, despite being offered additional training”.

“We work hard to accommodate our team’s needs, but like any employer, we ask our employees to meet certain minimum expectations and take appropriate action when they’re unable to do that,” Ms Nantel said.