Millions of British Facebook users’ phone numbers have been found online, according to a report.

The database included 18m phone numbers and their associated unique Facebook profile number or "ID" from the UK, a further 133m belonging to users in the US and more than 50m from Vietnam, TechCrunch reported.

The database, which was discovered by a cyber security researcher earlier this month, was not protected with a password. It has already been taken offline, but its creator has not been identified.

Facebook said that it had “no evidence” that Facebook accounts were compromised and claimed that the phone numbers had been taken from public accounts before the company changed its privacy settings last year.

It cut off a feature that allowed users to look up people using a phone number rather than a name after learning that malicious actors abused the feature to "scrape" phone numbers and email addresses. At the time it wrote that it believed "most people on Facebook could have had their public profile scraped in this way".

Although many might consider a mobile phone number public information, they are increasingly being used to get into bank accounts or other personal accounts. This can be done by fooling a telecommunications company support assistant into cancelling a SIM card over the phone, and requesting a new one.