Having said last week there would be "reduced work schedules" in May, Toyota's UK plant has now firmed up its plans: parts shortages from Japan mean only three days of half-shift working a week.

"The plant will have two days of non-production each week and limit production to half a shift on the other three days," Toyota Manufacturing UK said in a statement.

Workers will effectively get Fridays off - to be made up later. "Temporary flexible working arrangements have been agreed and will be adopted from 3 May to enable Fridays throughout May to be designated as a ‘non-attendance’ days. On these days employees will still be paid and work back these hours at a later date.

"The remaining non production time will be utilised for continuous improvement (kaizen) and training activities. The combination of this and flexible working arrangements will help ensure that we are able to quickly respond to the demand for our products as soon as parts are available."

The company said it would be 12,600 cars behind schedule in the UK by the end of May.

TMUK's Tony Walker told the BBC workers at the plant in Burnaston, near Derby, would remain on full pay and described the feeling amongst staff as "very positive".

"Everyone understands this is a unique situation. Usually our production is determined by demand, but demand is still there," he said.

"There is an understanding that this is because of the terrible situation in Japan and we just can't get the parts."

Toyota yesterday (20 April) announced the extension of three-days-a-week working to at least 3 June in the US, cutbacks in Canada and Chinese output down to 30% to 50% of normal, again due to a shortage of Japanese made parts as a result of the 11 March earthquake and tsunami in the north east.

"As we are producing, we are keeping a careful eye on the parts situation," Paul Nolasco, spokesman for Toyota Motor Corporation in Tokyo, told the BBC.

"We are doing the best we can to return the situation back to normal as soon as possible."

The company now faced a total production shortfall of 540,000 cars from North America, Europe, Japan and China for the period to 3 June, he said.

That is effectively 7% of Toyota's global production target of 7.7m units for 2011.

Latest US reports have suggested Toyota may revise its 2011 sales forecasts for North America at least and put back the launch of its iQ model as a Scion there.

Nissan's Sunderland plant in north east England will be closed from Good Friday (22 April) until May Day (1 May) while Honda from 11 April halved output at its Swindon factory earlier this month and has since said full production would not now resume until the end of May, extending delivery times for UK customers from four to eight weeks.

Japanese car exports fell 28% in March.