Inventories at U.S. wholesalers surged in December, posting their biggest gain since the summer of 2000 on a record rise in petroleum stocks, the government said on Friday.

The Commerce Department said wholesale inventories rose 0.8 percent, following a 0.3 percent gain in November. It was the biggest rise since June 2000. Sales at wholesalers fell sharply, dipping 0.8 percent in December.

The gain in inventories was larger than Wall Street had been expecting and was boosted by a record 16.5 percent rise in petroleum inventories at the wholesale level. Wholesalers may have turned more cautious and held more petroleum inventory on hand because of worries over a possible war with Iraq and a production halt in Venezuela, a major oil producing nation.

Forecasters polled by Reuters prior to the report's release had projected only a 0.1 percent gain in overall inventories.

The gain in inventories and the drop in sales in December combined to push up the stock-to-sales ratio, a measure of how long it would take to deplete inventories at the current sales pace. The ratio rose to 1.23 months in December from 1.21 in the prior month.