Oil prices rose to almost $72 a barrel yesterday on optimism that the global economy has reached its bottom, but the move prompted concerns that the doubling in crude prices since February could stem a recovery.

Oil prices fell in February to a four-year low of $32.70 a barrel, transferring wealth from oil- producing countries to consuming countries. But after a strong rally helped by the weakness of the dollar and resurgent inflows into commodities funds, West Texas Intermediate oil yesterday hit $71.79 a barrel, up $1.79 on the day.

Speculative positions in the New York energy market, betting that oil prices will rise further, are at their highest level since last July, while bankers report strong inflows into commodities funds from investors such as pension funds and retail.