British investors threw their weight behind Japan's pro-growth economic recovery plan in May, raising their investments in Japanese stocks to the highest level in more than a year.

In a monthly survey of 14 British-based investment managers, the average allocation to Japan in global equity portfolios rose to 9.2 percent, from 8.4 percent in April and the highest level since April 2012.

The bet on Japan was made against the backdrop of disappointing economic data elsewhere, including from China and the euro zone. Data from the UK has also been mixed and the average allocation to the UK in global equity portfolios was 22.8 percent, the lowest in 12 months.

Investors, however, warned that it was too early to judge whether Japan's massive unleashing of stimulus to try and revive the world's No. 3 economy, known as Abenomics after Prime Minister Shinzo Abe, will work.

"The US is slowing, China is not roaring, Europe is poor, the UK is struggling and Japan is yet to feel a genuine translation from early Abenomics," said Thomas Becket, chief investment officer at Psigma IM.

Some say Japan's efforts to weaken the yen will hurt other Asian markets and could spark competitive devaluation elsewhere. "Beware currency wars," said Lee Robertson, chief executive of Investment Quorum.

Average equity exposure in British asset managers' global balanced portfolios was 54.9 percent in May, the highest level in 14 months as investors pursued the higher returns on offer in stocks versus bonds, where returns are being curbed by injections of central bank liquidity.

Cash levels remained at 5.8 percent, having increased from 5 percent in January on concerns about the stability of world markets. The real estate allocation was 2.1 percent for the second month in a row and alternatives, which include hedge funds and commodities, dipped to 11.6 percent from 12.1 percent.

The poll was taken been May 16 and 21.

In a broadly insipid global economy, markets are scrutinizing the statements of U.S. Federal Reserve chief Ben Bernanke more closely than ever after minutes from a recent Fed meeting showed support for tapering the bank's quantitative easing stimulus program.

While the prospect of an early end to stimulus has unnerved equity markets in the past week, prolonged injections of liquidity would also pose risks.

"The risk is that he overcooks the pudding, which lets the inflation genie out of the bottle," said Robert Pemberton, investment director at HFM Columbus.

(Editing by Susan Fenton)