NEW YORK (CNNMoney.com) - Stock futures fell early Wednesday, reversing earlier gains, after the government's main inflation indicator came in higher than forecasts.

U.S. stock futures turned negative, indicating a lower opening for U.S. markets.

The U.S. Labor Department said its Consumer Price Index, its key inflation measure, rose by 0.6 percent in April.

Economists surveyed by Briefing.com forecast a 0.5 percent on higher energy prices, following a 0.4 percent rise in March.

The so called core CPI, which excludes energy and food prices, rose by 0.3 percent. Economists were looking for a 0.2 percent gain.

Investors have been particularly concerned about inflation pressures in recent days as they look for clues as to what the Federal Reserve will do with interest rates at its next meeting in late June.

Tuesday the core Producer Price Index, which measures inflation at the wholesale level, came in below expectations, helping to lift markets, but setting the stage for a possible sell-off if the core CPI doesn't follow suit, said Anthony Chan, chief economist for JPMorgan Private Client Services, just prior to Wednesday's CPI report.

"The market is so prepared for perfection after the core PPI on Tuesday," said Chan. "But this market is pretty nervous right now. If we get a core CPI reading of 0.4, the market will sell off very hard. A 0.3 reading will lead to a sizable but not as significant sell off."

Futures were higher before the inflation report after better than expected earnings gain from computer and peripheral maker Hewlett-Packard (Research) as well as from chip equipment maker Applied Materials (Research).

Shares of HP gained nearly 4 percent in after-hours trading following the report Tuesday, while Applied Materials initially rose, then fell on revenue guidance that was lower than forecasts.

Oil prices climbed above $70 a barrel in early trading after Iran rejected a European offer of a light-water nuclear reactor in return for giving up its own uranium enrichment program. But prices slipped back below that benchmark as trading got closer to 10:30 a.m. ET report on U.S. fuel inventories.

The June light crude futures contract for NYMEX was up 20 cents to $69.73 in electronic trading, while the July contract for Brent crude gained 16 cents to $70.24.

Gold also reversed recent losses and rose more than 2 percent to above $700 an ounce.

Major markets in Asia closed higher Wednesday as Japan's Nikkei snapped a six-day slide, while major European markets were mixed in early trading after minutes of the Bank of England meeting in May showed some central bankers there voting for a rate cut while others voted for a rate hike. England's central banks left rates unchanged at the meeting.

Treasury prices were lower, lifting the yield on the benchmark 10-year note to 5.14 percent from the 5.10 percent level reached late Tuesday. The dollar was lower against the yen and the euro.

For a more detailed look at the markets before the open, click here.