A journalist held after photographing a protest at an asylum centre has said “bad things are going on there” after weeks of protests and a Covid outbreak.

Calls to close the site at Napier Barracks in Kent, south-east England, have come from campaigners and politicians – but the Home Office said the barracks provided safe and secure accommodation.

Andy Aitchison, who documented a demonstration in which protesters threw fake blood at the gates, said he was arrested on Thursday at his home on suspicion of criminal damage and was held for seven hours at a police station where his memory card and phone were taken.

“There are obviously bad things going on there that they don’t want anyone witnessing,” he said.

“It’s the conditions there. They are cold, they have got one shower for 20 people, they are all sharing a room. They know that Covid-19 is rampant. They are worried about it and it’s not fair to anyone.”

The site was used to house about 400 asylum seekers until some were moved to self-isolation following a Covid outbreak.

Tensions at the barracks have been attributed not just to fears about the virus spreading, but also to uncertainty over asylum applications – along with the effect of housing traumatised people in an institutional, military setting.