* Prices rise 4.5 pct y/y, faster than expected
* Nationwide says house price growth to slow in 2017
* Shortage of new homes expected to underpin prices (Adds reaction, detail)
LONDON, Dec 29 (Reuters) - British house prices rose faster than expected in December, but the pace of growth is likely to slow in 2017 amid uncertainty about economic developments, mortgage lender Nationwide said on Thursday.
Annual gains stood at 4.5 percent in December, up from 4.4 percent in November. Economists polled this month by Reuters had expected to see growth of 3.8 percent.
Britain's property market slowed immediately after the vote in June to leave the European Union, but since then the economy has fared better then many economists expected and house prices have continued to rise.
Nationwide reiterated a forecast that house prices are likely to grow by around 2 percent in 2017, although the figure would depend on how the economy fares.
"The fact that the housing market is seemingly struggling to build momentum after coming modestly off its August lows reinforces our suspicion that it is likely to find life increasingly difficult as 2017 progresses," said Howard Archer, chief UK and European economist at IHS Markit.
Nationwide said low interest rates and a shortage of homes are expected to underpin support for prices.
Bovis Homes said on Wednesday it would not deliver the number of houses it originally expected in 2016, after about 180 sales failed to complete before the year end, resulting in a likely miss against market profit forecasts.
In December alone, house prices rose 0.8 percent after stagnating in November, Nationwide said. While the month-on-month measure can be volatile, this marked the biggest rise in a year.
Nationwide said 2016 was the first year since 2008 that house price growth in London was slower than the British average. (Reporting by Andy Bruce; Editing by Elaine Hardcastle and John Stonestreet)