* Average asking price rose 3.6 pct in four weeks to May 10
* Rise adds to concerns about a possible property bubble
* Asking prices in London rose 16.3 pct in May year on year
By Ana Nicolaci da Costa
LONDON, May 19 Asking prices for homes in Britain hit a new record high in May, adding to concerns about the speed at which the housing market is growing.
Asking prices rose 3.6 percent in the four weeks to May 10 - the biggest ever increase for this period - to an average of 272,003 pounds ($456,900). They were up 8.9 percent from a year ago, the highest annual rate since October 2007.
"May is a traditionally bullish price rise month, though this year's 3.6 percent jump beats the previous May high of 3.2 percent set in 2002," said Miles Shipside, Rightmove director.
"A late Easter in the heart of the house-hunting season has not only concertinaed the traditional hottest home-moving period by several weeks, but also stagnated seller numbers, further stirring up prices in areas of buoyant demand."
Britain's economy has been growing faster than most of its industrialised peers, with the housing market standing out as it benefits from falling unemployment, record low interest rates and government mortgage schemes.
Bank of England officials have been expressing more concern about the strength of the property market and targeted measures to curb it are expected in June.
BoE Governor Mark Carney on Wednesday again said the first line of defence against risks from the housing market would be to restrain mortgage lending rather than to raise rates.
The data supported the picture of a potential "bubble" forming in London while the rest of the UK was seeing more modest price growth.
Asking prices rose 16.3 percent in May year on year in the capital versus an average 4.9 percent rise in the rest of England and Wales.
"London prices traditionally pick up earlier than the rest of the country, and whilst it appears to be slowly dragging other regions along in its wake, the difference is still very marked," Shipside added.
The disparity between the property market in London, which attracts cash-rich foreign investors, and the rest of the country has prompted BoE officials to stress they do not set policy for the capital alone but for the country as a whole.
The Bank's chief economist Spencer Dale recently said the central bank "should be nervous" about the housing market, and deputy governor Jon Cunliffe said it would be "dangerous" to ignore its momentum.
Tougher rules for mortgage lenders came into force in April, requiring stricter checks on borrowers' ability to repay their loans.
Rightmove said the so-called Mortgage Market Review can help temper the wider market but that London needs a "major housing supply boost" to prevent excessive rises in house prices. ($1 = 0.5954 British pounds) (Editing by Susan Fenton)