Surging food prices boosted China's annual consumer price inflation to a 27-month high of 3.4 percent in May from 3.0 percent in April, the National Bureau of Statistics said on Tuesday.

Non-food inflation remained subdued, with prices up just 1.0 percent from a year earlier, but economists said the figures reinforced the case for higher interest rates to prevent banks' effective deposit rates from slipping further into negative territory.

"We expect tighter monetary policy in the coming months given heightened inflation risks and negative real interest rates," economists at Goldman Sachs said in a note to clients.

The overall figure was in line with the median forecast of a Reuters poll of economists, but Shanghai's benchmark stock market index fell 1.5 percent by late morning as investors started to price in expectations for a tighter monetary policy.

Food prices, which make up a third of the consumer basket, rose 8.3 percent in May from a year earlier; meat prices rose 26.5 percent.

Pork prices soared last month as a result of a widespread pig disease and a spike in the price of feedcorn, prompting Premier Wen Jiabao to show his concern by making a high-profile visit to a pork market in northwestern China.