Sadiq Khan has warned drivers not to be fooled by scam websites which claim to offer an easier way of paying the Ultra low emission zone (Ulez) charge.
The mayor urged people driving non-compliant vehicles within the zone to ensure they pay the £12.50 charge using the official Transport for London (TfL) website.
He added that TfL was working to ensure its website is promoted by Google over “third party” platforms in search results.
The warning came after Len Duvall, Labour group leader on the London Assembly, said one of his Greenwich and Lewisham constituents had been “duped” into paying the charge by online “scammers”.
He asked Mr Khan in a written question what he was doing to make people aware of where to pay.
The mayor said TfL “has no association with third party organisations who operate unofficial websites accepting payments of Road User Charging charges, usually at a higher rate”.
He said: “TfL encourages all motorists to use their official site to pay the charge. Paid-for search activity is being deployed so that Google’s search engine displays the official TfL website in a high position at the top or near the top of the page.
“Unfortunately, when people are searching to pay, internet search engines don’t always suggest the official TfL Pay to Drive web page at the top of their search results. This means that people may be offered a link to an unofficial payment site.
“The official TfL website advises customers how to avoid payment fraud, and TfL works proactively with search engine companies such as Google, as well as with Advertising Standards and Trading Standards, to remove unofficial websites entirely from the internet.”
TfL said some of these unofficial websites “claim to offer additional services” but that such services “are either non-existent or are already provided by TfL without charge”.
These sites can charge a premium of up to £8 extra, the organisation said.
They added that false claims are frequently made by these websites, such as stating TfL do not process payments securely, or that they share drivers’ personal data with others – neither of which are true.
The Ulez – which requires older, more polluting vehicles to pay the daily penalty if driving within the zone – currently covers the area within the North and South Circular roads, but is expanding on August 29 to cover the whole of Greater London.
The expansion plan has been blamed by senior Labour politicians as the main reason why the party lost last week’s by-election in Uxbridge and South Ruislip, but the mayor has said he remains committed to it, while “listening” to Londoners’ concerns.
Sources close to Mr Khan have suggested he is willing to consider additional measures to reduce the impact on low-income Londoners, but is not prepared to delay the zone’s widening or relax the enforcement rules.
A legal challenge has meanwhile been brought against by the expansion plan by five Conservative-run councils, with the High Court likely to issue its decision this week on whether the plan is lawful.