The former shadow minister was accused of “fragrantly flouting the law” after he posted a video of himself demonstrating in Westminster on Wednesday. He captioned the clip: "Been social distancing since March. Today I broke it to join the #BlackLivesMatter demo outside Parliament."
Mr Gardiner, who had been criticised for his actions by his colleague Lisa Nandy, issued a statement on the Labour Party website on Thursday morning, explaining his dual obligations to “set an example” and “call out racial injustice”.
He wrote: “Yesterday I joined thousands of young people marching against racial injustice and in protest at the murder of George Floyd.
Been social distancing since March. Today I broke it to join the #BlackLivesMattter demo outside Parliament and take a knee with thousands of brave young people calling for Justice. pic.twitter.com/1KWZeOPi01— Barry Gardiner (@BarryGardiner)June 3, 2020
“I took a knee as a mark of respect and paused with those remarkable young people to reflect on the racism faced by so many people of colour not just in the USA but here in Britain too.
“The number of people protesting made it impossible to observe the social distancing rules which I have strictly observed since March.
“I know how much people have suffered to keep each other safe and I apologise to them for the hurt my failure to observe the rules has caused.
“On Tuesday evening I received a negative test result. I am therefore confident that I did not infect anyone with whom I came into contact."
He continued by acknowledging the importance of health guidance, saying: "The rules are important in overcoming this epidemic and I do not want my action to undermine people’s willingness to maintain social distancing."
However, he added: “ My obligation as an MP is also to call out racial injustice and to stand in solidarity with the very people who, because of that injustice, are so much more likely to die from coronavirus.
"The anger generated by my breach of the social distancing rules must not be allowed to detract from the vital message that Black Lives Matter and that we all have an obligation to fight racism.
"The killing of George Floyd must be a catalyst for action.”
His statement came as fellow Labour MP Ms Nandy told Sky News that his failure to adhere to social distancing measures wasn't "right."
The Shadow Foreign Secretary told the broadcaster: "I don't think it was right, I think it was quite dangerous to break the social distancing measures.
"I completely understand what a lot of young people are coming out on to the streets of Britain to protest.
"I am very proud of them but social distancing matters.
"I want to see those young people making their voices heard, I don't want to see in hospital struggling to breathe with coronavirus."
She continued: "I think it was wrong for an MP out there saying overtly that he was not going to observe social distancing measures.
"These are the measures that have saved lives, that have stopped out NHS from becoming overwhelmed.
"Not just putting yourself at risk, you're also putting our NHS at risk and other people at risk.
"I hope he's reflected on that and decided to correct that because we can't give the impression that social distancing at this stage somehow doesn't matter as we come out of lockdown."
The day before, Tory MP Imran Ahman Khan said any ministers who broke social distancing rules to take part in the mass march should be prevented from returning to the Commons until after a period of isolation.
Mr Khan called on any MPs involved to be “prevented from rejoining this House until they have undergone a period of self-isolation” for the safety of all those working inside the parliamentary estate.
Deputy Speaker Dame Eleanor Laing said MPs who took part “have put themselves at risk” and “should act responsibly”.
After Mr Gardiner posted his protest footage on Twitter, Mr Khan said: “It has come to my notice that certain members of this House, including well-known members such as the member for Brent North (Barry Gardiner), have fragrantly flouted the law and have joined the protests outside, breaking – in fact boasting that they have broken – social distancing measures.
“I feel that we are going to be placed at risk when there has been such advertised and self-publicised breaking of the law and vectors of the disease that we are fighting, and that this Government is fighting, will be, if he returns to this House, a vector of the disease will be allowed access to spread amongst the hard-working staff here.
“Are there measures in order to make such members who have flouted the law and are now possibly more likely to be contagious or indeed infected by the disease to be prevented from rejoining this House until they have undergone a period of self-isolation to ensure that we do not suffer a threat because of their aberrant behaviour?”
Dame Eleanor told MPs that Commons Speaker Sir Lindsay Hoyle “has gone to a great deal of effort to make sure that members and staff working here are protected”.
She added: “If any member of this House is openly flouting the rules which we have asked every citizen of the United Kingdom to observe in order to keep this virus under control and to protect the vulnerable and to protect the NHS, then that member is putting not only himself or herself at risk, but is putting everyone else at risk as well.
“I hope that the facts are not as he has stated them, but if it transpires that the facts are as he has stated them then it should be incumbent upon anyone coming into this building, if they know that they have put themselves at risk of contracting or passing on the virus, that they should act responsibly.”