Mr Lamb last month called for a “fundamental” overhaul of the home help system, after a Telegraph investigation exposed more than half a million “drive-by” visits lasting less than five minutes.

Latest figures show 74 per cent of councils commissioning checks of just 15 minutes – a rise since 69 per cent in one year.

Care workers providing home visits say they have been told not to start up conversations in case it holds them up.

The new Nice guidance says visits shorter than 30 minutes should only be allowed if they are fulfilling “specific, time limited” functions – such as establishing medicine has been taken, or checking a person’s welfare – are part of a wider package of support, and involve a care worker who already knows the person.

Mr Lamb said: “This sets a standard for the first time. There will be no excuses from councils trying to justify rushed visits which deprive vulnerable people of human contact, and in some cases leave them forced to choose between help washing or dressing.”

He said too many councils were buying “time slots of care” which did not consider the actual needs of those receiving it, and meant elderly people barely had a conversation with those looking after them.

“Too often there has been a race to the bottom, with contracts simply competing on price, so that vulnerable people end up receiving care from a succession of different workers,” he said.

Mr Lamb said he had been appalled by recent cases he had encountered, with very vulnerable people having the most sensitive tasks carried out by strangers.

“In my own constituency I recently encountered a case of an old lady who had a succession of visits from different male care workers turning up to her bungalow in the evenings to give her a shower,” he said. “That is an assault on her dignity, it is not the way we should be providing care.”

Mr Lamb said: “We know there are too many examples of rushed care visits and it’s completely inappropriate to allow less than half an hour to help people eat, get dressed or get out of bed.

“That’s why we’ve asked NICE to look at this issue and develop guidance to make it crystal clear to councils that this culture of flying care visits must end. Both I and the public expect nothing less to make sure vulnerable and older people get the care they deserve.”

The Lib Dem care minister is calling on Labour and the Conservatives to join the Lib Dems and set up a non-partisan Commission on care, chaired by an independent expert to tackle the challenges of an ageing population.

Mr Lamb said: “If we do not face up to the growing pressures the system will crash. No party at the moment has come up with a plan to increase support for care.”

Cllr David Sparks, Chairman of the Local Government Association, said: “Short visits should never be the sole basis for care. However in some circumstances, such as administering medication, they can be appropriate, but only as part of a wider comprehensive care plan involving longer one-to-one visits.

“Sadly the rise in short visits is symptomatic of a social care and health system that continues to be chronically underfunded. Adult social care funding is in crisis and it is vital for our elderly population that government urgently addresses this.”