* Offer represented a 41 pct premium on March 16 close
* Hammerson says approach undervalues the company
* Raises doubts over Hammerson's acquisition of Intu Properties (Recasts story and adds background)
LONDON, March 19 (Reuters) - French shopping centers operator Klepierre has made a 4.9 billion pound ($6.9 billion) bid for Hammerson, seeking to strike before the British company completes a major takeover of its own.
Klepierre said on Monday that it had made a 615 pence-a-share proposal to buy the company behind Birmingham's Bullring center and London's Brent Cross, a cash-and-paper bid that it said was rejected by the British group in less than 24 hours.
Hammerson shares surged by 24.5 percent to 544.4 pence at 1515 GMT on news of the approach.
The swoop by the French group threatens to scupper Hammerson's own plan to acquire another London-listed shopping center operator.
Last December, Hammerson, which also owns Bristol's Cabot Circus and a stake in the Bicester Village retail outlet, agreed an all-share offer to buy smaller rival Intu Properties in a deal that valued Intu at about 3.4 billion pounds.
Hammerson's investors are yet to approve that takeover, leaving Klepierre, which wants to buy Hammerson on a "standalone basis," with a window to disrupt the deal.
Furthermore, prior to Monday's jump, Hammerson's share price had slumped by about 18 percent since the Intu takeover was announced. That fall had left Hammerson vulnerable to an approach by the French group, analysts said.
PLUGGING A GAP
Paris-based Klepierre owns more than 100 shopping centers across 16 countries but does not have any sites in the UK and Ireland, a gap that a takeover of Hammerson would resolve. Like other shopping center operators, Klepierre is also grappling with fierce competition from online retailers such as Amazon, a rivalry that is driving consolidation across the commercial property sector.
Indeed, just days after Hammerson announced the Intu deal in December, Europe's biggest property firm Unibail-Rodamco agreed to buy U.S. and UK mall operator Westfield Corp for $16 billion.
Hammerson said on Monday that it remained "fully committed" to the acquisition of Intu, the owner of Manchester's Trafford Centre.
Klepierre's bid offered a 40.7 percent premium to Hammerson's closing share price on March 16, the last trading day before its approach was made public, the French group said.
It added that its aim was start to a "constructive dialog" with the British company.
But Hammerson hit back by saying that the offer significantly undervalued it because it was 20.7 percent lower than its net asset value per share of 776 pence as of the end of December.
The bid was on the basis of 50 percent in cash, and the other half in Klepierre shares.
"The proposal from Klepierre is wholly inadequate and entirely opportunistic," Hammerson chairman David Tyler said. "It is a calculated attempt to exploit the disconnect between our recent share price performance and the inherent value of our unique and irreplaceable portfolio which is delivering record results."
Hammerson shares have fallen amid investor worries that the Intu deal raised its exposure to a difficult UK retail market and diluted its higher quality portfolio.
Analysts at Jefferies said on Monday that Hammerson's Intu tie-up was "losing credibility" and that it was "easy to see why the market isn't supporting" the deal.
Shares in Klepierre, which counts U.S.-based Simon Property Group as its biggest investor, were down 4 percent.
"I'm guessing Klepierre's shareholders fear the company will be back with an improved (more expensive) price in a very difficult market (commercial real estate) and they don't want to hear about a bidding war," said a Paris-based trader.
Shares in Intu, which Simon Property tried to buy in 2011, were up 4.6 percent at 213.5 pence.
Under British takeover rules, Klepierre now has until April 16 to make a firm offer for Hammerson or walk away. Hammerson shareholders are expected to vote on the Intu deal next month, although a date has not yet been set. ($1 = 0.7117 pounds) (Alan Charlish contributed reporting from Gdynia, Poland Editing by Richard Lough and Keith Weir)