Concerns about fraud have prompted fund-raising website JustGiving to review all pages raising money for the victims of the Westminster attack.
Money raised for victims will not be automatically released until verified.
For the first time, the company has taken direct control of a crowd-funding page, which any individual can set up.
Concerns were raised over a fund for the family of Aysha Frade, after a person who set up the page had the same name as a woman convicted of fraud.
A crowd-funding page can be set up for free by any individual person for any personal cause – from a memorial fund to a holiday.
People can donate money to the cause via the website and, when the fund-raising time period is up, JustGiving send the total amount direct to the user, minus a 5% fee.
Following Wednesday’s attacks a numbers of crowd-funding pages were created on JustGiving for victims’ families.
More than £17,000 has been raised for Ms Frade, who was killed on Westminster Bridge on Wednesday.
But well-wishers who did an internet search of a person listed as creating the page, discovered someone with the same name had been convicted of benefit fraud in 2013.
JustGiving also discovered the account username had been changed a number of times since it was first set up.
In an unprecedented move, JustGiving took the decision to take over the page from the initial user.
They also added a “Verified by JustGiving” label to the page to assure users that money raised would go to Ms Frade’s family.
A similar label has appeared on a page for PC Keith Palmer, who was murdered outside Parliament.
On Saturday afternoon, this had raised more than £690,000.
There are a number of other crowd-funding pages for Aysha Frade on JustGiving that remain unverified.
But the site has said all pages relating to the Westminster attack have been placed into “quarantine” as a matter of caution, so that no funds will be automatically released to users without review.