The 'impossible task' for Norfolk and Suffolk landowners of dealing with ragwort could be tackled by low level criminals and out-of-work youngsters, a former cabinet minister has claimed.

Lord Tebbit made the comments in a letter to Matt Shardlow - chief executive of a charity called Buglife - who is concerned about the effect of declining ragwort on bees and rare insects.

The peer, who now lives in Bury St Edmunds, famously suggested in 1981 that the unemployed should get on their bikes to find work.

In the letter, given to a national newspaper, the peer wrote: 'I suggest you come to the Norfolk/Suffolk border areas of East Anglia. Landowners who wish to control ragwort face an impossible task when roadside verges are dominated by it to an extent I cannot remember in the past.

'There would be little cost to bring that under control if Neets and low level criminals were required as part of their contribution to the society which finances them, or which they have abused … to uproot this weed.'

He later told the Guardian: 'Given a bit of organisation, they [unemployed young people] would be happy doing something constructive. That's something constructive for them. It's appealing, it gets rid of a weed which is a danger to some animals and helps landowners in the cultivation of their land.

'That was my thought that caused me to suggest the idea … in a way it's a form of national service, of doing something for society in a way in which anyone unless they are physically disabled can participate.'

Asked whether he acknowledged some might find the idea of forced labour in return for benefits controversial, he said: 'It's workfare but I think there are some powerful arguments for workfare and so does [Labour MP] Frank Field for example. It's not a way-out idea in that sense.

'If you go back to the Beveridge report on which the whole welfare state has been based, you'll find he took the view that youngsters who had never worked should not receive benefits because they have not contributed anything.

'I am much more modest about this than Beveridge was and I suspect Ernie Bevan might have been on my side in it. I just think a lot of those youngsters want something to do which is constructive.'

Shardlow, the chief executive of Buglife, said: 'We were surprised that Lord Tebbit suggested that the unemployed and criminals should be forced to pull up ragwort, particularly as ragwort is an important part of our native biodiversity, supports 30 species of insects and helps to sustain the now fragile bee populations that we need to pollinate crops.'

Norwich South Labour candidate Clive Lewis said: ''To compare young people to criminals is appalling. I'm sure the thousands of young people in Norwich looking day in day out for a decent, well paid, secure job, would be all too happy to disabuse him of his Victorian, work-house mentality. They'd happily explain to him how his government has presided over ever increasing low-pay, zero-hour contracts, under-employment and job insecurity.'

While Jessica Asato, candidate for Norwich North said: 'This is what we've come to expect from the nasty party. Instead of acknowledging how hard it is still for young people to find a job, Norman Tebbit is back demonising a generation of youngsters, many of whom have sent hundreds of CVs off and spend their time volunteering to get the experience they need. Thirty years later it's no longer on yer bike, but on yer knees.'