MP Caroline van der Plas from the pro-farming BBB party, has said she is withdrawing from all public appearances for a time after receiving a string of threats.

‘I do not feel safe at the moment,’ Van der Plas said on Thursday, after RTL Boulevard broke the news. ‘The anti-farmer or anti-BBB lobby is working flat out at the moment. I’m getting more hate mail and death threats.’

A spokesman for the party said that an investigation into the threats is now underway.

The MP, whose party is riding high in the opinion polls, has condemned the radical farmers’ motorway campaign, telling the AD on Wednesday that while protests on the edge of motorways is fine ‘dumping manure on the road and setting fires in the verges is risking the safety of others’ is not.

‘I support all action which is within the law,’ she said. ‘I understand farmers’ emotions and I support their battle.’

Her decision to step back and cancel media and work appointments comes as prime minister Mark Rutte urged people who have been threatened by radical farmers and their supporters to make a formal police report.

Workers brought in to clear up asbestos which had been dumped on one motorway downed tools on Wednesday after receiving threats, forcing officials to find a new contractor.

Rutte, who is currently on holiday, described the current wave of protests by radical farmers as ‘unacceptable’.

‘Deliberately endangering others, damaging our infrastructure and threatening people who are helping clean up the mess is going way beyond the limit,’ he said on Twitter.

‘There are enough other ways to express your discontent within the law,’ he said. ‘Most farmers are doing that.’

Read our December interview with Caroline van der Plas

As yet, no-one has been arrested for dumping manure, asbestos and other farm waste on motorways nationwide over the past two days. A police spokesman told RTL Nieuws that police are first looking at the resources they have – such as camera footage and eyewitness accounts.

The police will ‘definitely try’ to trace those responsible for the dumping, he said. ‘But investigations take time,’ he said. ‘First you have the footage, then you have to track down the person.’

So far, the dumping is known to have caused at least three accidents but no injuries.