Crude oil prices jumped to a 2-1/2-year peak on Monday as worries about supply disruption increased due to widening clashes in Libya, while world stocks fell on concern sustained high oil prices could hurt growth.

Unrest in the oil-rich Middle East stoked demand for precious metals, with gold -- often sought in times of geopolitical tensions -- rising close to a lifetime high at $1,434.82 an ounce, while silver surged to a 31-year peak.

The euro briefly reversed gains against the dollar and peripheral euro zone debt prices fell after Moody's cut its rating for Greece by three notches to B1 and kept it on review for further downgrades, although core German debt was little changed.

U.S. crude oil futures jumped 1.6 percent, topping $106, to their highest price in 30 months as a counter-offensive by Libya's Muammar Gaddafi against rebels deepened fears that Africa's largest holder of oil reserves is headed for civil war.

U.S. crude is up by more than a fifth in the last two weeks.

Investors are worried that a prolonged period of high oil prices could stifle economic growth and erode corporate profits, while adding to inflationary pressures.

The MSCI all-country world stock index was down 0.4 percent, with European stocks weighing on the benchmark.

Investors are still nervous. The one thing they hate is uncertainty and the Middle East situation is providing plenty of uncertainty, said Keith Bowman, analyst at Hargreaves Lansdown.

A majority of countries have to import oil. It's a major cost and a sustained period of elevated oil prices is seen as a major drag on industries.

The FTSEurofirst 300 index of top European shares was 0.3 percent lower, tracking falls in Asian equities overnight and after Wall Street ended lower on Friday, erasing last week's gains.

Japan's Nikkei average ended down more than 1 percent.

EURO SLIPS ON GREEK RATINGS CUT

In currencies, the euro reversed early gains against the dollar after the Moody's action, but later rose to a four-month high of $1.4014 after breaking above resistance at $1.40 on Friday.

Some analysts said uncertainty about the euro zone's more indebted countries could hamper future gains by partially offsetting expectations of an interest rate hike from the European Central Bank.

People are a bit hesitant about taking euro/dollar above $1.40 despite the factors playing in its favor -- interest rate differentials and high oil prices, said Niels Christensen, currency strategist at Nordea in Copenhagen.

There's a bit of bad news with the Greece downgrade and Ireland wanting to renegotiate the bailout, and there's some focus on this, but it's too early for concerns about sovereign debt to really come back and hurt the euro.

U.S. and German government bond prices were flat on the day, shrugging off Moody's rating decision on Greece.

This is not going to be the last downgrade for Greece. The market has already discounted that Greece will need to restructure its debt, so the rating agencies are just running behind the market, said Christoph Weil, an economist at Commerzbank.

(Additional reporting by Atul Prakash and Jessica Mortimer; Editing by Catherine Evans)

Japan Libya Energy