Thirty-three rightwing extremists were held under anti-terror laws last year, a steady rise which coincided with another decrease in the number of Islamist extremists detained.

The figures, released by the Home Office, compare with the 28, 10 and six people from a suspected far-right background who were detained in previous years.

By comparison, the number of suspected Islamist extremists being held peaked in the 12 months to the end of June 2017, when 185 people believed to have Islamist extremist ideologies were in custody in prison and on remand for a terror-related offence.

It dropped to 178 last year, and 171 in the 12 months to the end of June this year, according to the figures which were published on Thursday.

The far-right cohort includes individuals from politically far-right groups such as National Action, which became the first extreme rightwing group to be proscribed as a terrorist organisation in 2016.

Individuals who were found guilty of membership of National Action last year included a neo-Nazi couple who named their baby son after Hitler and

a British army veteran who served in Afghanistan.

The security minister, Brandon Lewis, said of the latest figures: “These statistics show just one part of the breadth of work undertaken by the government, police, security and intelligence agencies and local authorities to reduce the terrorist threat.

“From arrests and prosecutions to safeguarding and early intervention through our Prevent programme, we will continue to do what it takes to keep the public safe.”

However, the comments from Lewis come as the Home Office continues to face criticism that it is not taking the far-right threat seriously enough. A study by a Whitehall thinktank of far-right fundraising activities found that an “unwillingness” by the UK government to engage with the threat was creating a vacuum in which such groups could flourish.

Overall, there were were 266 arrests for suspected terrorism-related activity in the last year, down from 354 in the previous 12 months, in what is a continuation of a downward trend.

Of those arrested in 2018/19, nearly a quarter (23%) were released without charge – the lowest percentage since records began following the 11 September terror attacks in 2001.

In 2017/18, nearly half (48%) of all those arrested were released without charge, down from 53% the previous year.

British prisons held 218 people in custody for terrorism-related offences as recently as 30 June, according to other Home Office statistics, a figure which was unchanged since the previous year.

Of those, 78% were categorised as holding Islamist-extremist views while a further 15% were categorised as holding far rightwing ideologies. The remaining prisoners, 6%, held beliefs related to other ideologies.