Dozens of MPs have called on Andy Burnham to introduce an 18-week target for dementia diagnosis in the NHS.

The cross-party group of MPs, which includes former secretaries of state, warned that the Prime Minister risks sending 'entirely the wrong signal' if he fails to improve how patients suspected of having the debilitating brain condition are diagnosed.

The NHS is required to diagnose patients with cancer or heart disease within strict time frames, but there is no such measure for dementia despite it claiming 76,000 lives a year as Britain's biggest killer.

One in three people living with dementia in England do not have a formal diagnosis, and the remainder waited an average of three and a half years before getting one.

Meanwhile, the time dementia patients must wait between being referred to a memory clinic by their GP and getting a diagnosis has increased by almost 70 per cent since 2019, soaring from 13 weeks to 22 weeks, according to the latest figures.

Charities warn that the lack of a firm target means services could be cut back, with more patients left waiting months or years while their condition worsens.

This could mean they become too far progressed to benefit from breakthrough drugs, which must be taken in the early stages of the disease.

The letter to Mr Burnham, co-ordinated by Tory MP Joe Robertson, was backed by more than 60 MPs and included former secretaries of state Sir Iain Duncan Smith, Sir Andrew Mitchell, Dame Karen Bradley and Kit Malthouse, and Commons select committee chairmen Sir Geoffrey Clifton-Brown, Dame Caroline Dinenage, Bob Blackman and Layla Moran.

The letter, seen by the Daily Mail, says: 'With the possible advent of transformative drugs, a timely and accurate diagnosis is essential.

'While progress has been made in reducing elective care waiting times through the Government's commitment that 92 per cent of referral-to-treatment pathways are completed within 18 weeks, dementia remains without a comparable standard.

'We are concerned that silence on the 18-week diagnosis target would send entirely the wrong signal and leave dementia services fragmented across the country.'

Mr Burnham has told how his father is unaware he has become Prime Minister because he is living with Alzheimer's disease.

Alzheimer's Society chief executive Michelle Dyson warned the Government's dementia plan - called the Modern Service Framework for Dementia and Frailty - will not be 'worth the paper it is written on' after the target, which appeared in an earlier version, was removed from the latest draft.

She said the framework was supposed to be a ten-year plan to transform care for the one million people in the UK living with the disease, but she now has 'very little confidence' in the document because the ambition appears to be 'extremely low'.

The Daily Mail and Alzheimer's Society have partnered in the Defeating Dementia campaign, which aims to raise awareness of the disease in an effort to increase early diagnosis, boost research and improve care.

In an exclusive interview with the Daily Mail last month, Ms Dyson accused the NHS of treating dementia patients like 'secondclass citizens' who are simply 'cast aside' and typically sent home with little more than a leaflet.

The Department of Health and Social Care has acknowledged dementia has a 'devastating impact' on people living with the condition and on the families who care for them. A spokesman added: 'We want everyone affected to be able to access high-quality, personalised support.'