Adult social care services are facing a “deluge” of requests for support from vulnerable and older people as society starts to open up after the pandemic, according to council care chiefs in England.

There has been a big increase in people needing help after their condition deteriorated while waiting to be admitted to hospital for treatment, as well as a surge in those needing support after being discharged from hospital.

An ongoing lack of resources – English councils have lost £7.7bn from adult social care budgets between 2010 and 2020 – means people needing support face longer waits for less care, the Association of Directors of Adult Social Services (Adass) warned.

Local authorities were also facing a spike in demand for social care support for people with mental illness, victims of domestic violence and abuse, and rough sleepers, a survey of Adass members found.

The huge strain on unpaid carers during the pandemic was also highlighted: two-thirds of directors reported increases in requests for support from carers who had experienced breakdown or illness, possibly as a result of the stress of being unable to access support services for long periods under lockdown.

According to Carers UK, 4.5 million people became unpaid carers in the weeks after the first lockdown in 2020, on top of an estimated 9 million carers before Covid-19. However, the closure of daycare facilities and a move to online services during the pandemic meant this group became “more hidden than ever”.

Stephen Chandler, the president of Adass, which carried out the survey, said: “Some of the numbers we are seeing are phenomenal. The trends are unsustainable and show why the government must publish its plans for social care as a matter of urgency.”

Chandler added that the survey underlined the urgency of the need for reform of adult social care funding. “Adult social care has stepped up during the pandemic and is providing care and support for many more people who have been unable to get admission to hospital and for many more who have been discharged. Without social care, the NHS would collapse.”

Meanwhile, a cross-party group of MPs said the pandemic showed the UK could not afford more broken promises on adult social care, and called on the government to set out a comprehensive funding plan by the end of the year.

“The pandemic has shone a light on the sector and underlined how vital it is to so many, while emphasising that care is not properly funded, lacks transparency and urgently needs reform,” a report by the public accounts committee (PAC) said.

The committee added it was sceptical ministers could be relied on to deliver change, however, saying social care reform had not happened despite two decades of green papers, white papers, reviews and political commitments.

Meg Hillier, chair of PAC, said: “The reforms to address this now must include a long-term funding plan that allows local authorities and providers to innovate and improve services. We cannot afford more broken commitments on care.”

The government has promised to set out proposals to overhaul social care funding by the end of 2021.