Workers at dozens of DVLA offices are staging a 24 hour strike today in a dispute over closures and job losses.
Members of the PCS union at 39 local and 10 enforcement offices in England, Scotland and Wales are taking part in the industrial action.
The union is campaigning against planned office closures across the country, arguing it signals the end of a "highly prized" face-to-face service to motorists.
The union has delivered a seventy two thousand name petition opposing the closures, to the Department for Transport.
"As well as losing a high quality public service and more than 1,000 jobs at a time of high unemployment, we believe these closures will lead to increased vehicle tax evasion and fraud.
"We want the minister to listen to the overwhelming views of the public, motor traders and his staff, and to see sense and reverse these ill-thought through and damaging closures."
DVLA said it could not guarantee a business-as-usual service because of the strike and asked people to avoid travelling to any DVLA office today.
Contact centres will be operating a reduced service and callers were warned to expect longer waiting times.
DVLA offices facing closure in Wales are:
More top news
Welcome to the Newsweek Quiz - where we'll be testing your knowledge from the last seven days of news in Wales.
Pensioner arrested following the death of a woman on the day he stepped onto tracks at Cardiff Central Station.
Walk-on actor John Lewis was jailed for fraudulently claiming £70,000 while working on Casualty and Sherlock.