WASHINGTON (AFP) - US retail sales fell for the first time in eight months in May, the government said Friday, casting doubts on consumer spending, a linchpin of economic growth. Sales unexpectedly dipped 1.2 percent to 362.5 billion dollars from April, according to data from the Commerce Department. Most economists had expected a 0.2 percent sales rise in May following a revised 0.6 percent gain the month before. Excluding autos, retail and food services sales fell 1.1 percent from the previous month, the department said. Sales in May dipped at building supply stores, reversing more than half of the surge in the previous two months, while many other segments posted big falls, including general merchandise stores, auto dealers, gas stations and apparel stores. Non-store retailers and furniture stores were seen as bright spots. The monthly retail sales report is a key indicator of consumer spending, which accounts for two-thirds of US output. Economists say consumer spending will be vital to a sustainable recovery as the government starts to wind down extraordinary stimulus measures.