Hurricane Igor Packs a Punch in Atlantic Ocean

* Igor could become Category 5 storm on Monday

* No immediate threat to land or energy interests

* Tropical Storm Julia moves over eastern Atlantic

MIAMI (Reuters) - Hurricane Igor churned westward in the Atlantic Ocean as a dangerous Category Four storm and could strengthen even further Monday, forecasters said.

Igor, capable of causing catastrophic damage, posed no immediate threat to land or energy interests.

The U.S. National Hurricane Center said Igor packed maximum sustained winds of 150 miles per hour and Monday could turn into a Category Five storm on the five-step Saffir-Simpson scale of hurricane intensity.

Behind Igor, Tropical Storm Julia developed over the far eastern Atlantic Ocean Sunday, becoming the 10th named storm of the 2010 Atlantic hurricane season.

Igor, the fourth hurricane of the 2010 Atlantic season, was located about 940 miles east of the Caribbean's northern Leeward Islands at 5 a.m. EDT, the Miami-based center said. Hurricane force winds extended outward up to 40 miles from the center and tropical storm force winds reached out up to 175 miles, it said.

Igor is moving west and is expected to turn toward the west-northwest and slow its pace by late Monday or Tuesday.

"Some fluctuation in intensity is likely during the next 48 hours and Igor could become a Category Five hurricane today (Monday)," the center said.

A Category Five hurricane has sustained winds topping 155 mph.

Computer models project Igor would stay in the Atlantic for the coming days and not enter the Gulf of Mexico, where U.S. oil and gas operations are clustered.

Veteran forecaster Jeff Masters said Sunday on his Weather Underground blog (www.wunderground.com) that Igor may threaten Bermuda but had only a small chance of making landfall on the U.S. East Coast or in Canada.

Masters and other forecasters said it was still too early to make any definitive predictions about Igor's long-term fate.

Meanwhile, Tropical Storm Julia also posed no immediate threat to land and was heading in a westerly direction as it swirled off the Cape Verde islands. It packed top sustained winds of 40 miles per hour, the hurricane center said.

"Some strengthening is forecast during the next 48 hours and Julia could become a hurricane in a couple of days," the center said.

At 5 a.m. EDT, Julia was located about 30 miles south-southwest of the Cape Verde Islands.

Most forecasters predicted the 2010 Atlantic hurricane season to be extremely active. Besides Igor, three hurricanes -- Alex, Danielle and Earl -- formed earlier in the season, the last two reaching Category 4 strength.

The hurricane season runs from June 1 through Nov. 30 and is currently in its peak period.

(Reporting by Tom Brown; Editing by Will Dunham)