Devon's MPs are being asked to lobby government ministers for more money amid planned cuts to homelessness funding in the county.

Devon County Council (DCC) is consulting on proposals to cut some adult social care services, including its £1.5 million contribution that help prevent people becoming homeless.

It insists no decision has yet been taken but says it can no longer afford the money, diverting it instead towards spending in other areas that support vulnerable children, young people and adults.

Local charities have hit out at the plan. YMCA Exeter, which receives £150,000 in support from the council, says "the consequences for vulnerable young adults will be huge," while St Petrock's, a charity in Exeter, warned it could lead to a "homelessness crisis" in the city.

Now the Exeter Homelessness Forum has written to Devon's MPs to inform them of the plans, while asking them to lobby ministers to "provide the desperately needed funding to avoid DCC precipitating a homelessness crisis in Devon."

Its letter, signed by a number of local stakeholders including charities and housing associations, warns that the £1.5 million cut will result in a "significant increase in the numbers of people being forced to live on the streets through the closure of services that this fund supports."

The money currently pays for contracts with five providers who support around 250 people at any one time.

Their services are provided in multiple occupancy hostels in Exeter, East Devon, Torridge and North Devon, as well as through a countywide floating support service. None of the money pays for accommodation.

The letter says: "The removal of this funding will bring about the loss of vital skilled and professional support, which enables people with complex needs to establish and maintain accommodation after a period of homelessness."

It adds: "According to the Devon County Council's own impact assessment this could trigger the closure of 'five hostel provisions' across the county, creating an inevitable and significant increase in homelessness and rough sleeping.

"This is in addition to a very large number of people who are homeless but hidden from view – for example sofa surfing or in B&B accommodation – many more of whom are likely to end up rough sleeping without these services."

The forum goes on to warn MPs that the budget's removal will mean the government's policy of ending rough sleeping by the end of this parliament will be "completely – and very visibly – unachievable in Devon."

It also says that should the proposal go ahead, it will end up costing other services such as district councils, the police, NHS and social care "significantly more in the medium to long term."

A spokesperson for Devon County Council recently said: "We've budgeted this year to significantly increase spending in services that support vulnerable children, young people and adults, to meet rapidly growing demand for those services.

"To prioritise spending on our statutory responsibilities, we have to make savings in the region of £45 million from elsewhere and get the best possible outcomes from every single penny we spend.

"While we've been able to help fund this support service in the past, even though it falls outside our statutory adult social care responsibilities, sadly, we can no longer afford to do so.

"Reluctantly, we are therefore proposing to stop our contributions to this contract and instead target our scarce resources to support growing numbers of vulnerable adults who are eligible for social care support."

They added: "We will not make a decision regarding this proposal until we've considered the consultation responses, and we encourage people in the meantime to let us know what they think."

The public consultation is open until Wednesday 19 April.