SAN FRANCISCO, California (Reuters) -- Using 4 million computers worldwide, scientists based at the University of California, Berkeley said that they have identified about 150 sources of possible signals from intelligent civilizations.

The California researchers plan to head to Puerto Rico this month to use one of the world's most powerful telescopes to more closely investigate the signals that might be from extra terrestrials, a university spokeswoman said.

"They are homing in on interesting signals," said Sarah Yang, a spokeswoman at the University of California, Berkeley where the SETI+home research project is based. "They have not said they found anything."

Linking computers
The project links volunteer computer users into the researchers' efforts to search for strong or unusual signals from space that one day may lead to the proof that there really may be something else out there.

The leading candidate signals compiled over more than three years of work are the ones that were particularly strong or have been observed in the same spot more than once, researchers said.

While scientists involved in the project are cautious about their chances of actually discovering a signal from an intelligent being in outer space this time, they believe they are on the right track for the future.

"I believe that we will likely discover extraterrestrial civilizations in the next hundred years," Dan Werthimer, chief scientist of SETI+home said in a statement.

"Even if we don't find a signal from ET this time, I'm optimistic in the long run, since our search capabilities are doubling every year."