But the broad strength of commodity prices may also reflect the appeal of the sector as an "alternative asset"...

That has led to the launch of whole series of exchange traded funds based on commodities, which have made the asset class accessable for a much wider range of investors....

Robin Bahr, a metal strategist at UBS, says investors seem to feel they have an each-way bet on commodity prices. Either global economic growth is strong and supply remains tight, or the world slips into stagflation, as it did in 1970s. Commodities should perform well either way.