Sainsbury’s has apologised to two men who say they were asked to follow a security guard out of a shop after another customer complained about them holding hands and putting their arms around each other.

Thomas Rees said he and his partner, Joshua Bradwell, had been left stunned after the security guard led them out of a Sainsbury’s branch in Hackney, east London, and told them a woman had complained about their behaviour in the aisles.

After he tweeted his anger at the supermarket chain, he was offered an apology and a £10 voucher. But he has said he now feels uncomfortable at the prospect of returning to the shop and running into the security guard again or discovering other customers with intolerant views.

“We weren’t celebrating good news, we weren’t all over each other, we weren’t in the throes of passion – it was essentially just holding my boyfriend’s hand as I do every day,” he told BBC News.

Rees said he and Bradwell had just paid for their items on Monday evening when the security guard approached them and asked them to follow him outside. He said he was left “stunned and shaking” by what the guard told them.

The 32-year-old told Buzzfeed News: “I just don’t understand why he needed to take us outside and why he needed to tell us. There was no sense of humility.

“I refuse to believe this would have happened to a heterosexual couple – we just stared in disbelief. The issue here is it felt like like 1960s Britain.”

After the incident, and despite doubts over whether to speak out about it, Rees decided to vent his anger on Twitter, writing: “To the bigot who complained about my bf & I holdin hands & the security guard at @sainsburys who felt the need to ‘talk’ to us outside [middle finger emoji].”

To the bigot who complained about my bf & I holdin hands & the security guard at @sainsburys who felt the need to 'talk' to us outside🖕🏻 — Thomas Rees (@doganddinosaur) August 8, 2016

Rees’s subsequent comments suggest he does not necessarily blame the security guard for the situation. He told the BBC: “I do feel for the security guard because he was clearly unable or poorly equipped to handle these situations.”

Rees is calling for Sainsbury’s to make sure that staff are properly trained to handle similar situations in the future. It is not the first time that the retail giant has faced criticism over allegations of homophobia. Activists staged a “kiss-in” protest at a Brighton branch in 2014 after two women were threatened with ejection after sharing a kiss.

A Sainsbury’s spokesperson said an investigation into the incident was continuing, adding: “We sincerely apologise to Thomas and Josh. We are an inclusive retailer and employer and do not tolerate discrimination in our stores. We will take appropriate action once we’ve concluded our investigation with our security contractor.”