UPDATE 2-Light premiums weigh on UK insurer Hastings despite profit rise

* FY adjusted operating profit rises 39 pct to 184.1 mln stg

* FY Gross written premiums rise 21 pct, below estimates

* Says competitive environment continues to be intense

* Shares fall over 10 pct(Adds analyst, CFO comments, share movement, details)

By Noor Zainab Hussain and Carolyn Cohn

March 1 (Reuters) - British insurer Hastings Group HoldingsPlc reported a 39 percent jump in full-year adjustedoperating profit as it provided insurance to more customers andincreased its market share, although a slowdown in premiumswritten took some of the shine off results.

The company, which mainly sells motor insurance in the UK,said adjusted operating profit rose to 184.1 million pounds($253.36 million) for 2017 from 132.1 million pounds a yearearlier.

Gross written premiums rose 21 percent to 930.8 millionpounds, about 2.5 percent below consensus estimates, missingboth Barclays and RBC expectations.

Hastings' shares were down 7.1 percent at 290.4 pence at0944 GMT, making them the biggest percentage losers on the FTSEMidcap Index.

"The results are good - but the stock is a growth stock, andgrowth has markedly slowed as the competitive environment hasgot tougher," Barclays analyst Alan Devlin told Reuters.

Hastings offers private car insurance, home insurance,motorbike and van insurance and premium financing and ancillaryproducts. It has made headway in a competitive sector byfocusing on selling motor insurance via price comparisonwebsites.

Companies such as Admiral, Direct Line andesure also provide motor insurance in Britain.

"The competitive environment continues to be intense, withslower premium inflation since the end of the third quarter thanthat experienced in the first half of 2017 following theproposed Ogden rate review," said Gary Hoffman, the company'snon-executive chairman designate, referring to the change in theway personal injury lump-sum payments are calculated.

Premiums rose in the first half of 2017, partly in responseto the new rules for personal injury claims, but reversed courseto fall in the next two quarters after Britain said it plannedto change the way the payments are calculated, a move whichwould cut the size of those payments .

"As you look into the future, we would expect premium ratechanges to follow claims inflation, with some uncertaintysurrounding the proposed changes to the Ogden rate, and alsofrom the planned whiplash reforms," Hoffman said.

Whiplash is a form of neck injury caused by a sudden joltthat snaps the head backwards, which insurers say has resultedin many fraudulent claims.

"It (whiplash reforms) is likely to be in 2019 now. Theimpact should be lower claims. The industry, as they see claimscost come down, will adjust premiums accordingly," CFO RichardHoskins told Reuters.

($1 = 0.7266 pounds)

(Reporting by Noor Zainab Hussain in Bengaluru; editing byAmrutha Gayathri, Larry King)