Image caption The union believes the plans will have a bad effect on both the public and offenders

Thousands of probation officers in England and Wales have walked out on strike over the government's plans to privatise large parts of the service.

Members of the National Association of Probation Officers (Napo) began the 24-hour strike from midday on Tuesday.

The union previously registered a trade dispute over proposals to transfer most of the service to private companies such as G4S and Serco.

The Ministry of Justice (MoJ) said the strike was "disappointing".

'Communities at risk'

The action by Napo will be only the union's fourth strike over a century.

Napo general secretary Ian Lawrence said union members were entering "unprecedented times" in their bid to "save the probation service".

"They strongly believe, along with other criminal justice agencies and experts, that [Justice Secretary] Chris Grayling's plans will undermine public protection and put communities at risk whilst also not providing the adequate service offenders need to turn their lives around," he said.

Napo said 80% of members voted to go on strike on a 46% turnout. The union said 7,500 staff would be affected.

Some £450m worth of contracts has been offered to private and voluntary sector organisations.

This covers the supervision of 225,000 low and medium-risk offenders a year on a payment-by-results basis.

'Status quo'

The contracts will be spread across 20 regions in England and one in Wales.

A new public sector National Probation Service will deal with 31,000 high-risk offenders each year.

The MoJ said more than 700 organisations from across the world had expressed an interest in the private contracts,

Last week, the chairs of three probation trusts wrote to Mr Grayling expressing their concerns about the plans, and the possible risks to the public.

Napo suggested there were concerns about how the system operated in the US, where some states have outsourced their probation service.

Justice minister Jeremy Wright described the strike as "in favour of the status quo".

"It is disappointing Napo has chosen to strike when we are making positive progress, in meaningful discussions with them and other relevant trade unions as we transfer to the new arrangements," he said.

"This is a strike in favour of the status quo, which is high reoffending rates and no support for 50,000 short sentenced offenders each year who are currently released without any supervision and go on to commit so much crime in our communities.

"We have well established contingency plans to deal with any potential action. We will continue to support staff and engage with unions as our important reforms move forwards."