A view of Google's Beijing offices. File photo: VCG

Google on Monday fired four employees on the grounds they violated data security policies, prompting ire among colleagues concerned it was retaliation for worker organizing.

One of the workers fired was connected to a petition against Google working with the US immigration and border patrol agency. She confirmed her firing in a message posted on Twitter.

A memo to employees titled "Securing our data" sought to correct what it contended was misinformation about the purported wrongdoing, saying it involved "systematic searches for other employees' materials and work," according to reports by US media.

Google, the money-making engine of parent company Alphabet, confirmed a copy of the note published by Bloomberg but declined to comment further.

However, a Medium account connected to a massive walkout by Google employees last year argued that the four workers were fired in an attempt to crush efforts to organize staff.

"Four of our colleagues took a stand and organized for a better workplace," read the post by Google Walkout for Real Change. "When they did, Google retaliated against them."

Authors of the post contended that Google policies on data security were tightened to provide cover for getting rid of workers involved in efforts to unionize.

"They think this will crush our efforts, but it won't," the Medium post said. "One of the most powerful companies in the world wouldn't be retaliating against us if collective action didn't work."