* Greek car sales down 21.6 pct -LMC
* Western Europe registrations up 14.3 pct to 1.31 mln
* Britain's June sales up 12.9 pct in record first-half (Recasts with Greece figures)
FRANKFURT/LONDON, July 6 (Reuters) - Greece suffered the sharpest drop in new car registrations of any western European car market in June, falling 21.6 percent year on year amid political uncertainty in the run-up to the country's bailout referendum, industry data showed on Monday.
Official figures for Greece will not be provided until Friday, but data from consultancy LMC Automotive showed that sales fell to 6,247 new vehicles in June.
By contrast, registrations in western Europe rose 14.3 percent to 1.31 million as Britain, Germany, France and Spain delivered double-digit percentage gains. Almost all major markets performed well, helped by extra selling days.
"Despite growing concerns over Greece's future in the euro zone and the implications for the currency union, the car market in western Europe grew strongly in June and in the first half of the year," LMC Automotive analyst Emiliano Lewis said.
"While uncertainty created by the Greek crisis clouds the picture for the coming months, after a strong start we still expect 2015 to be up comfortably on last year."
Though fleet renewals by car rental companies had caused Greek auto registrations to jump 43 percent in April, that masked the longer-term downward trend.
Registrations of new passenger cars in Greece fell 73.5 percent last year, following a 78.3 percent decline in 2013, the Greek Association of Motor Vehicle Importers Representatives said, adding that demand between January and May had fallen by about 70 percent.
The only other European markets to post year-on-year declines in June were Ireland and Finland, dropping 14 percent and 2.5 percent respectively, LMC said.
For western Europe as a whole, however, sales continued to rise, with June's 1.31 million new registrations lifting the seasonally adjusted annual sales forecast to 13.22 million, up from May's forecast of 12.51 million.
First-half sales were up 8 percent, according to the LMC data, which is compiled from published registration figures and projections for some smaller markets.
Britain's June sales rose 12.9 percent to 257,817 vehicles, helping to post the country's strongest half-year performance on record, the Society of Motor Manufacturers and Traders (SMMT) said on Monday. First-half sales were up 7 percent, though SMMT expects slower growth for the remainder of the year.
"(It) is encouraging to see more consumers choosing British models. This is important for the wider economy, with 799,000 people now employed across the UK automotive sector, including retail," SMMT Chief Executive Mike Hawes said.
"We anticipate a flatter second half of the year as the market finds its natural running rate."
June sales in Germany, Europe's largest auto market, rose 13 percent to 313,600 cars, the VDA industry association said last week, extending the year-to-date advance to 5 percent, or 1.62 million autos. (Reporting by Edward Taylor and Andy Bruce; Editing by Dale Hudson and David Goodman)