Charities are to be forced to draw up written agreements showing how vulnerable people will be protected from aggressive fundraising tactics, the prime minister has said.
David Cameron said the actions of some fundraisers were damaging the reputation of the charity sector.
The changes will be introduced in amendments to the Charities Bill.
Fundraising methods have come under scrutiny since the death of poppy seller Olive Cooke, 92, in May.
An inquest found Mrs Cooke, from Bristol, had received 267 charity letters in one month, leading to suggestions that the hounding for money pushed her to take her own life. Her family insist the charities were not to blame.
The prime minister said: “Our charities undertake vital work, bringing communities together and providing support to some of the most vulnerable members of our society.
“But the conduct of some fundraisers used by them is frankly unacceptable and damages the reputation of the sector as a whole, which is why we’re introducing a new law to make sure charities raise funds in the right sort of way.”
By political correspondent Ross Hawkins
The conduct of charity fundraisers is under scrutiny like never before following the death of Britain’s oldest poppy seller – 92-year-old Olive Cooke.
Thought to have taken her own life, she had been exhausted by requests for money from charities, according to a friend, and had set up 27 direct debits to make donations – although her granddaughter told an inquest that letters seeking money were not a factor in her death.
The issue, and an investigation into fundraisers’ call centres by the Mail on Sunday, has attracted the attention of ministers.
Now a new law will oblige charities and organisations that raise money on their behalf to state in their contracts how vulnerable people are to be protected and there will be a review to consider whether further action is needed. Fundraising bodies have already pledged to strengthen protections.
Under the new rules, charities with incomes of more than £1m will set out in their trustees’ annual report their fundraising approach.
This will include the use of professional fundraising agencies, as well as steps to prevent inappropriate fundraising from vulnerable people, such as the elderly and people with Alzheimer’s.
The legislation would also require all professional fundraisers to set out in their agreements with charities what steps they are taking to protect vulnerable people from high-pressure tactics.
Minister for Civil Society Rob Wilson said the new laws would have “some impact on charities” but they should understand that the “loss of revenue will come if these scandals continue to go on”.
He warned that a failure to respond could result in full regulation of the charity sector, which “would incur big costs for charities”.
He added that the government has also set up a review panel to look at measures to stop fundraisers finding “ways around the system”. The panel will report by September.
‘It felt like harassment’
Kate Schofield from Huddersfield told BBC Radio Four’s Today programme she received about 30 calls after donating to a well-known charity by text message.
“I answered a TV charity appeal for Syrian refugees and donated via text. It was not long after that I started receiving quite a lot of cold calls and this went on and on.
“I actually ended up getting about 30 or 40 phone calls from them. They were not even starting to take “no” for an answer so it did start feeling like harassment.
“After about a couple of weeks, I was on holiday. I was getting about 10 phone calls a day.
“I was ignoring them because it was going to cost me a lot of money to answer them. But I did feel like every time I looked at my phone there was a missed call from the same number.”
Sir Stuart Etherington, chief executive of the National Council for Voluntary Organisations (NCVO), is to conduct the review to decide whether more powers are required.
“For every challenge we face, there is a charity that will help – be that facing cancer or saving our precious green spaces,” he said.
“They are able to do this because of the trust, confidence and overwhelming generosity of the British people.
“We simply cannot allow aggressive fundraising tactics to damage this trust. Charities must maintain the highest standards, including taking a firm grip on how the agencies they employ are interacting with the public,” Sir Stuart added.
Leading UK charities Oxfam, the Salvation Army and Save the Children have welcomed the prime minister’s proposals.
Tanya Steele of Save the Children said their supporters were their lifeblood and the sector had to improve to strengthen faith and trust.
Oxfam chief executive Mark Goldring said the British public were “amazingly generous” and he hoped a balance could be found so people could give without receiving unwanted calls.
Last month, Oxfam suspended operations with a call centre after claims in the Mail on Sunday that Listen Ltd staff used high-pressure fundraising techniques.
The company said it trained employees in accordance with regulators’ requirements and would investigate.
Some laws around charities are devolved to Scotland. A Scottish government spokesman said fundraising controls have served Scotland well but it was “always looking at improvements” and would look closely at the PM’s proposals.