Police want new and expanded rights to access medical records and other confidential data without an individual's consent, a senior police chief has told the Guardian.

Sir Peter Fahy, the Greater Manchester chief constable, said the extra access to sensitive data was needed to help police cope with growing numbers of vulnerable people.

Fahy said police frequently dealt with people struggling to look after themselves, including elderly people, people with dementia or Alzheimer's, those with drug or alcohol problems, those with mental health issues and problem families. Perhaps most controversially, he said medical professionals should share information about women suffering from domestic abuse, even against the victim's wishes.

He said demands had changed over the past two decades, with vulnerable groups now accounting for around 70% of police work. "We need to have easier access to information," he said.

Fahy cited the example of basic information such as next of kin for people with Alzheimer's or dementia, access to which, he said, would enable police to contact relatives and get basic details such as medical history, who a person's doctor is, and what exactly they are suffering from.

Too often officers responded to a 999 call with inadequate information, he said, and getting the information, even if possible, took too long. "We need to get it in 20 minutes at 3am."

Fahy accepted the public may be sceptical about his calls for greater powers but said privacy concerns which either deny officers access to information or slow the process down cost police money and time.

He said the challenges of a changing society – with people living longer and increasingly on their own – were falling on the police, who were the "service of last resort", and expressed fears that police and other public services could be swamped by growing demands.

"We could do a better job if we have greater access to information, which it is currently hard for us to get," he said. "It would give us a deeper understanding of those we are expected to help and their problems. The actions we take would be much improved if we had a better understanding of that history at the time we are called."

Police have long been in conflict with the medical profession over access to sensitive information, with doctors arguing that patient privacy is their prime concern.

Dr Tony Calland, of the British Medical Association, said: "The essential principle that runs throughout the recording of medical information is that of confidentiality and trust. This principle has stood the test of time for millennia and still holds good today.

​"​At present the checks and balances in the current legal position are satisfactory and whilst the current law may cause some difficulty for the police the case has not been made to recommend a substantial change in the law ​."​

Fahy, one of the most senior chief constables in Britain, said he had been in initial talks with the government about increasing police access to confidential information. He said it could also help others such as social workers to solve the problems that vulnerable people face.

Fahy believes a national register of vulnerable people should be created. Some may choose to opt in to the register and agree to agencies such as police and social services having greater access to their private data in an emergency. But others could have such information shared without their consent by agencies which are trying to solve their problems and protect them from harm, Fahy said.

A more controversial example is a woman suffering from domestic violence, where Fahy said doctors or medical professionals would know or suspect there was a problem but not tell the police or other agencies.

Fahy said agencies might need to radically rethink the way they work. He said medical professionals could breach confidentiality and share information to prevent further harm.

In return police would promise not to "put the door in and arrest", and work with agencies to solve the problem: "The alternative is the woman continues to suffer … There should be the ability to share the information, against the woman's wishes, to solve the problem, without a criminal justice system approach. Society has matured – there is a far greater expectation on public services to safeguard vulnerable people.

"Twenty years ago, with domestic abuse, it was seen as one of those things. Now there's a greater expectation agencies will safeguard the victim whether or not they wish to make a complaint and enter the criminal justice system."

Fahy said an "industry of case conferences and referral forms" had sprung up as police tried to get the information they need from other agencies. He believes this is a drain on police time and resources at a time when budgets are being cut.

He accepted that trust in state power had been damaged after the revelations from the whistleblower Edward Snowden about the extent of state surveillance: "The danger is [revelations] from Snowden create an atmosphere of suspicion of why public services want to access the information."

But he said: "If you want a good public service it is crucial that there is increased information sharing, properly overseen and regulated."