BEIJING, April 1 (Reuters) - Growth in China's services sector cooled slightly in March and hovered near one-year lows, an official survey showed on Wednesday, adding to concerns that the economy is losing more momentum.

The official non-manufacturing purchasing manager's index, or PMI, fell to 53.7 from February's 53.9, hugging the one-year low of 53.7 struck in January.

The 50-point level separates growth from contraction on a monthly basis.

The services sector was the lone bright spot in China's slowing economy last year, expanding strongly and creating more jobs even as activity in the factory sector fizzled. But activity readings have been uneven in recent months, raising concerns that service companies may be finally succumbing to the broader economic downdraft.

Weighed down by a property downturn, factory overcapacity and high levels of local debt, China's economic growth is expected to slow to a quarter-century low of around 7 percent this year from 7.4 percent in 2014, even with additional policy easing measures.

Services accounted for 48.2 percent of the economy in 2014, up from 46.9 percent in 2013, while the secondary sector, which includes manufacturing and construction, accounted for 42.6 percent of the economy last year, down from 43.7 percent.

(Reporting by Kevin Yao; Editing by Kim Coghill)