LONDON (Reuters) - A run-up in asking prices for newly listed homes in Britain has lost steam ahead of an increase in property purchase taxes, according to a survey published on Monday.

Property website Rightmove said the average price of properties put on the market rose by 0.5% between Jan. 12 and Feb. 8 to 367,994 pounds ($464,666), a weaker-than-usual increase for the time of year and a slowdown from a strong rise of 1.7% in the previous four weeks.

Compared with the same period a year ago, asking prices were 1.4% higher.

Colleen Babcock, Rightmove's head of partner marketing, said the March 31 end of the temporary tax break - for buyers in England and Northern Ireland of cheaper homes and for first-time buyers - was having an impact.

She warned some buyers might end up missing the deadline due to a logjam in conveyancing work.

"It would seem justifiable for the government to announce a short extension before the end of March," Babcock said.

Rightmove said the number of new properties coming to market was up 13% from a year earlier while buyer demand was 8% higher and agreed sales had risen by 15%.

Britain's housing market gained some momentum last year on hopes that borrowing costs would fall although the slower-than-expected pace of rate cuts has weighed on demand.

The Bank of England reduced its benchmark Bank Rate from 4.75% to 4.5% on February 6 but said it would move gradually and carefully when considering further changes to borrowing costs.

($1 = 0.7920 pounds)

(Writing by William Schomberg; editing by David Milliken)