Car users in the UK have begun receiving letters notifying them their vehicles are among the thousands caught up in the Volkswagen diesel emissions scandal.

The letter, from Volkswagen director Alex Smith, confirms the vehicle is roadworthy so there is "no need" to take immediate action.

It adds: "However, a service action including your car will be required to rectify the issue.

"Technical solutions are currently being developed and the matter is being worked upon with the utmost priority."

Motorists have not been told when their vehicles will be recalled, although Volkswagen bosses yesterday said that process is expected to begin in the new year.

The German car giant today confirmed it will switch to new diesel emissions technology in Europe and North America following the scandal, after admitting 11 million of its vehicles worldwide are fitted with software which was used to cheat environmental tests in the US.

Yesterday, the UK boss of Volkswagen apologised "sincerely and unreservedly" to customers.

In a grilling by the Commons transport committee, Paul Willis conceded there was "some risk" that a target of doing all the work by the end of next year would be missed.

Some 400,000 would need changes to their fuel injection systems as well as having the software removed, he said - though he was unable to give any technical explanation to the frustration of MPs.

The emissions scandal was sparked by US environmental regulators who found that VW had installed defeat device software which switched engines to a cleaner mode when they underwent official testing.

Once on the road the cars produced nitrogen oxide pollutants at up to 40 times the legal standard.