Oil prices start 2012 up nearly 4 percent

NEW YORK (AP) — Oil prices are soaring today as tensions grow over key Persian Gulf oil shipments.

In afternoon trading benchmark crude jumped $3.80, or 3.8 percent, to $102.63 per barrel in New York. Brent crude, which is used to price foreign oil varieties that are imported by U.S. refineries, rose $3.87, or 3.6 percent, to $111.25 per barrel in London.

Prices climbed as soon as exchanges opened for the first day of 2012 trading. Commodity prices tend to rise at the beginning of January as investors start the new year with a fresh round of trading.

This year prices were driven by heightened concerns that Iran might try to close the Strait of Hormuz in the Persian Gulf to oil tankers, if Western nations impose new sanctions.

Iran warned the U.S. to stay out of the strategic waterway, where one-sixth of the world's oil shipments pass every day. On Monday its navy fired a cruise missile as part of a military exercise.