The biggest US police union is pressing Amazon to follow Walmart and remove from third-party sale a shirt that seeks profit in relation to the Black Lives Matter protest movement.

The shirt, which carries the words “Bulletproof: Black Lives Matter”, was removed from online sale by Walmart on Thursday, after the Fraternal Order of Police (FOP) said it was “offensive”.

In an open letter, FOP president Chuck Canterbury appealed to Amazon chief executive Jeff Bezos to support the FOP in “increasing the bonds of trust between the men and women of law enforcement and the communities they serve”.

The shirt was still available for sale via Amazon.com on Friday. Amazon declined to comment.

Speaking to the Guardian, Canterbury said he was not surprised, describing Amazon “as a pretty liberal marketer”.

The issue was relevant, he said, because of the “amount of violence demonstrated at Black Lives Matter marches and the fact that eight police officers had been assassinated while protecting Black Lives Matter protests”.

Canterbury said he was referring to officers who were shot in separate incidents in Dallas and Baton Rouge last summer.

The gunmen in those shootings were not affiliated with the Black Lives Matter movement. In Dallas, a gunman shot dead five officers during an anti-violence protest. In Baton Rouge, three officers were killed in an ambush.

Canterbury told the Guardian he believed nonetheless that anti-police rhetoric in the name of the protest group “had inspired people of feeble minds to strike out at police officers”.

“It happened as a result of the rhetoric of different BLM groups,” he said.

Messages seeking comment from prominent Black Lives Matter activists were not immediately returned.

In his open letter to Walmart, Canterbury accused it of allowing third-party sellers to profit from racial division.

“Commercialising our differences will not help our local police and communities to build greater trust and respect for one another,” he wrote. “Turning a buck on strained relationships will not contribute to the healing process.”

He added: “I wanted to let you know that my members are are very upset that you and Amazon are complicit in the sale of this offensive merchandise.”

Walmart said in a statement that after “hearing concerns from customers” it had dropped the third-party sale of the “bulletproof” merchandise.

Like other online retailers, it said, it would continue to offer third-party merchandise that carried protest and counter-protest slogans such as Black Lives Matter, Blue Lives Matter and All Lives Matter.

The third-party vendor selling the “bulletproof” shirts was Connecticut-based Old Glory Merchandise. Calls to the company were not answered on Friday. Owner Glenn Morelli told CNN, however, that he had already decided to remove the shirt from his site.

“It wasn’t a big seller at all,” he said. “The Blue Lives Matter sells more than the Black Lives Matter or bulletproof shirts combined. We don’t like to offend anybody.” He added: “You have to sell all different kinds of shirts. It’s hard to make everybody happy.”

On Friday, Amazon customer reviews for “bulletproof” merchandise offered by one-third party merchant mirrored the divisive national debate over the Black Lives Matter movement.

One reviewer, PhantomOfAmazon, wrote: “The slogan is divisive & misleading. Black Americans must come together to solve their issues in areas like Chicago, Detroit, Oakland, LA, etc.”

Another, Vincent Alexander, commented: “Great shirt, unless you hate freedom of speech.”

According to the National Law Enforcement Officers Memorial Fund, 64 US law enforcement officers have been shot and killed in 2016, the most in five years.

The Counted, a Guardian project to record the number of people killed by law enforcement in the US, has recorded 1,045 such deaths in 2016. Last year, the total was 1,134. The Black Lives Matter movement has grown around such deaths, in high-profile cases often of unarmed African American men.

Canterbury said “over 95%” of fatal shootings by law enforcement came during engagements with armed suspects.

“There’s a big differences between shooting someone assassination-style while they’re enforcing the law and being shot while breaking the law and not complying with a lawful arrest,” he said.

Guardian analysis of the 2015 figures showed young black men were nine times more likely than other Americans to be killed by police officers.

A US government pilot program to count killings by police has recorded a sharply higher number of deaths than previous official efforts. Department of Justice officials have said their new method for counting “arrest-related deaths” should improve the “reliability, validity and comprehensiveness” of such information.

Canterbury said FOP members would continue to apply pressure on retailers to drop such merchandise, “until Black Lives Matter makes statements that they do not approve of violence”.