Shares in Waterloo, Ont.-based Research in Motion rose to new heights on Thursday amid rumours that the maker of the popular BlackBerry device was being eyed by Microsoft Corp.

Google recently announced it's interested in making its own mobile phone operating system to compete with Microsoft's Windows Mobile, triggering the software giant's interest in RIM.

But neither Microsoft nor RIM responded to the report, saying they would "not comment on rumours or speculation."

That didn't stop RIM's stock from closing up 91 cents to $84.59 on the Toronto Stock Exchange Thursday.

At one point the stock rose as high as $89.68. More than 1.7 million of RIM shares moved during the day, most in the morning.

In the past, rumours have swirled about Microsoft and Motorola considering buying the company, with some analysts calling it a regular occurrence.

In recent weeks RIM has shown strong growth, with the growing popularity of the BlackBerry smartphone, often referred to as the "CrackBerry" for its addictive nature.

The company has had a record-breaking earnings period and is now worth nearly $50 billion in market capitalization.

Analyst Barry Richards, of Paradigm Capital in Toronto, told The Canadian Press that as RIM continues to grow, several companies have lost their chance to acquire it.

"We are running out of possible acquirors and we are now left with Cisco, Microsoft, IBM and maybe Nokia," he said.

"In the end, RIM is all about its CEOs . . . and neither seem to have any interest to be acquired, so (it's) hard to believe it could happen."

With a report by The Canadian Press