* China's Jan average new home prices rise 5 pct y/y
* Jan new home prices +0.3 pct m/m - Reuters calculations
* Beijing's prices +0.2 pct m/m, Shanghai and Guangzhou -0.4 pct (Recasts, adds national data and background)
BEIJING, Feb 24 (Reuters) - China's new home prices in January grew 5 percent from a year earlier, data from the statistics bureau showed on Saturday, even as the government continued its efforts to rein in speculative demand to fend off bubble risk.
The government removed the sales prices for affordable housing from the latest monthly calculations, distorting comparisons with previous months' growth data.
Average new home prices in China's 70 major cities rose 5 percent in January year-on-year and 0.3 percent month on month, according to Reuters calculations based on the official survey.
That compared with December's annual growth of 5.3 percent and 0.4 percent growth month on month, which included affordable housing.
The National Bureau of Statistics said in a statement that prices were "stable while slightly lower" last month, as eleven major cities fell year on year.
"The housing prices in tier-one cities reversed from growth to a decline and there was a slowdown in the growth rate in tier two and three cities," it said.
Last month, Beijing's new home prices rose 0.2 percent month on month, while Shanghai and Guangzhou prices fell 0.4 percent and the market in Shenzhen was unchanged, data showed.
China's housing market has boomed since late 2015, giving a major boost to the economy but stirring fears of a property bubble even as authorities are trying to contain risks from a rapid build-up in debt.
Home prices have slowly levelled out and even softened in the country's biggest cities under the weight of increasingly tough cooling measures, though some smaller cities are still seeing appreciable rises.
(Reporting by Josephine Mason and Pei Li; Editing by Jacqueline Wong)