A threat by an Iranian leader to halt supplies sent oil prices sharply higher on Monday, pulling stock market futures lower to start the week.

The Euro Dollar Pit at the Chicago Mercantile Exchange, May 10, 2006. [Reuters]

S&P 500 futures fell 3.7 points at 1,284.50 and Nasdaq 100 futures weakened 6.5 points at 1,608.00.

The decline came as oil futures shot up by more than $1 in electronic trade, following a threat by Ayatollah Ali Khamenei to energy supplies.

"If you make a wrong move regarding Iran, definitely the energy flow in this region will be seriously endangered," he said on state television, the BBC reported.

Iran, the world's fourth-largest oil exporter, is at odds with the U.S. and the Europe over its nuclear research program, which many in the West feel is aimed at developing nuclear weapons.

In overseas trade, European stock markets headed lower, though oil producers including BP advanced on the rising energy prices. Major Asian stock markets were mixed.

Meanwhile, the euro touched a new 2006 high at $1.2979, while the yen was mostly steady against the dollar.

The euro's advance came after continued to reaction to Friday's U.S. job report, which showed that only 75,000 nonfarm jobs were added to payrolls in May.

U.S. investors were torn over the data, with some taking cheered that the data means it's less likely than the Federal Reserve will hike interest rates, while others were concerned about the economic growth implications of the below-trend jobs report.

U.S. stock markets on Friday sputtered to a mixed end of the week, with the Dow industrials and Nasdaq Composite finishing lower, while the S&P 500 ended up 2.5 points.

This week's U.S. economic release calendar isn't seen as quite as crucial to determining the Fed's future path after Friday's jobs report.

On Monday, the Institute of Supply Management's May services index is due for release, with economists polled by MarketWatch expecting a slowdown to 60.5 percent from 63 percent.

Any figure above 50 indicates economic expansion.

Pharmaceuticals may also see attention after a key cancer drug conference.

Amgen Inc., AstraZeneca, Bristol-Myers Squibb, GlaxoSmithKline and ImClone Systems were among the companies presenting data at the American Society of Clinical Oncology annual meeting.

Chesapeake Energy agreed to buy various energy assets for $932 million. It said it's paying $2.10 per thousand cubic feet equivalent for the 1.5 trillion cubic feet of natural gas assets.