* MSCI world equity index down 0.5 percent at 243.30
* Oil below $69 a barrel on dollar, ample supply concerns
* Government bonds, dollar firmer
By Natsuko Waki
LONDON, June 22 (Reuters) - World stocks slipped on Monday and government bonds rose as a decline in oil and commodity prices weighed on resource stocks and caution ahead of this week's data weighed on risky assets.
U.S. crude oil fell 1.8 percent to $68.30 a barrel, hit by a firmer dollar and weak gasoline prices after investors grew concerned there would be ample fuel supply in the United States to meet demand during the summer holiday season.
A fall in energy prices hurts profits on energy companies, which make up nearly 22 percent of the equity index in London.
General concerns about the economy persisted with the World Bank warning that the prospects for the global economy remained unusually uncertain.
Angel Gurria, head of the Organization for Economic Cooperation and Development, also warned in an interview with Reuters that major economies will contract this year and the issue of unemployment will linger.
"The worst should be over but the ongoing improvement is likely to be too weak to seriously discuss a recovery," said Carsten Brzeski, economist at ING Financial Markets.
MSCI world equity index fell 0.5 percent, after posting its first weekly loss since mid-May last week.
Oil and gas shares were down more than 2.5 percent and were one of the biggest losers of the day.
Copper futures eased more than 3 percent to a three-week low, driven by a firmer dollar and demand worries.
The FTSEurofirst 300 index fell 1.3 percent, led by energy shares. Mining stocks rose after global miner Xstrata said it wanted talks with its rival Anglo American about a proposed merger of equals worth about $68 billion.
Anglo American's shares rose nearly 10 percent at one point.
Emerging stocks lost half a percent on the day. U.S. stock futures were down around 0.9 percent, pointing to a weaker open on Wall Street later.
Even with a recent setback, world stocks are up more than 7 percent this year.
"We've been comfortable in overweighting equities. In equities, we expect modest double digit or high single digit returns this year," Rick Lacaille, chief investment officer at State Street Global Advisors, told Reuters television.
"We remain of the view that equities offer a reasonable value. There's enough return for us to overweight."
A closely-watched German Ifo survey showed investor morale improved in June, with its business climate index rising to 85.9 from an upwardly revised 84.3 in the previous month.
FED MEETS
The euro was the day's major loser, falling 0.8 percent to $1.3835, ahead of the European Central Bank's first ever one-year refinancing operation on Wednesday, aimed at getting banks lending again and reducing the cost of borrowing for banks, firms and consumers.
The dollar rose 0.6 percent against a basket of major currencies ahead of the Federal Reserve's monetary policy meeting later this week.
Investors are split on whether the Fed will expand its existing $300 billion plan to purchase Treasuries when it meets.
If the Fed announces a plan to expand its purchase programme, investors who had fled Treasuries in search of higher yields might return to lock in recently elevated yields.
"Even though yields have soared, there are no concrete signs that lending in the economy is picking up steam and other monetary indicators such as the money multiplier is still near post-collapse levels," UBS said in a note to clients.
"Our economists expect changes in the FOMC statement will reflect a bit more optimism on the prospects for recovery but also a stronger signal that there will be no rush to unwind stimulus."
The benchmark 10-year Treasury yield fell slightly to 3.7377 percent
The June Bund future rose 18 ticks.
Investors were also cautious ahead of a record $104 billion auction of Treasuries this week.
(Additional reporting by Tamawa Desai and Farah Master; Editing by Victoria Main)