Members of the Council of the Royal College of Physicians (RCP) have written to prime minister Theresa May to voice serious concerns over the capacity and resources needed to help the NHS cope with demand.

The letter, signed by RCP president Professor Jane Dacre and 49 members of Council, representing 33,000 doctors across 30 specialties as well as 750 physician associates, warns that the increase in patient need is outpacing the resources available, that services are "too often paralysed by spiralling demand to transform and modernise", hospitals are "over-full, with too few qualified staff" and services are "struggling or failing to cope".

It stresses that "current investment levels are not sufficient to meet current or future patient needs", and called for immediate "reinvigoration of social care services" and "urgent capital investment in infrastructure," to help address the threat to patient care quality.

The move comes as NHS chief executive Simon Stevens warned MPs this week that issues being faced by the health service will get worse this year, and also rejected the prime minister's claim that government has given the NHS more money that it requested.

"I think it would be stretching it to say the NHS has got more than it asked for," Stevens reportedly said. "There are clearly very substantial pressures, and I don't think it helps anybody to try and pretend that there aren't."

"Emergency Departments are overflowing with patients, internal major incidents are being declared around the country and staff in EDs are struggling to cope with the immense demand being placed on their services," noted Dr Taj Hassan, president of the Royal College of Emergency Medicine. "These crowded environments are stretching the clinical workforce to their limits and, more importantly, at times are unsafe for patients".

"It is essential that the NHS receives adequate investment and sufficient resources to keep up with demand and deliver the quality of care that people deserve. Without dedicated funding and planning, both patients and staff will increasingly suffer."