BlackBerry maker Research In Motion Ltd announced a share buyback worth up to $1.2 billion on Thursday, driving up its share price, but analysts said competitive concerns will continue to exert pressure on the company's stock.

Shares in RIM climbed 3.2 percent after the Waterloo, Ontario-based company said it would repurchase about 21 million shares, or 3.6 percent of outstanding common shares on Nasdaq.

Although the share repurchase should give investors some comfort, we believe headwind concerns will likely remain, putting the onus on the company to continue to disprove market concerns through earnings strength, UBS analysts Phillip Huang and Maynard Um said in a note on Thursday.

RIM said the share repurchase program, which will run up to 12 months or until purchases are completed, may commence on Nov. 9.

RIM's share value dropped more than 6 percent on Monday after Citi Investment Research analyst Jim Suva told investors to sell the stock because an invasion of new phones, applications and competition pose a risk for BlackBerry.

Suva also said that some wireless carriers are likely to slow promotional spending on BlackBerry and shift it toward other phones.

Last month, RIM rolled out an updated version of its top-end BlackBerry Bold. The device is aimed at reasserting RIM's dominance in the professional market at a time when its retail consumer business is under growing pressure from Apple's iPhone.

Shares of the company rose $1.85 to $59.46 on Nasdaq on Thursday morning and were up C$1.97 at C$63.36 on the Toronto Stock Exchange.

($1=$1.06 Canadian)

(Reporting by Susan Taylor and R. Manikandan in Bangalore; editing by Peter Galloway)