UPDATE 1-TGS says no legal basis for Wavefield merger delay

(Adds Wavefield statement, details, shares)

OSLO, Nov 20 (Reuters) - Norwegian seismic group TGS (TGS.OL) said on Tuesday it sees no legal basis for peer Wavefield Inseis' WAVE.OL decision to delay their planned $1.2 billion tie-up and that it was reviewing its legal options.

Wavefield shareholders voted late on Monday to delay the merger after allegations by some Wavefield owners that TGS may have withheld information about its results ahead of a profit warning that knocked the shares of both groups.

The warning lowered the value of the all-share deal to Wavefield owners by about $200 million.

"There is no legal basis for a delay in the merger," TGS-Nopec said in a statement on Tuesday. "TGS-NOPEC is reviewing its full range of legal alternatives and its rights under Norwegian law."

The merger is set to create a company better able to compete with bigger rivals in scanning for oil and gas deposits beneath the sea floor.

Shares in Wavefield were up 0.2 percent at 41.20 crowns, while TGS-Nopec was off 1.1 percent at 75.20 crowns. Oslo's benchmark index .OSEBX was up 1.1 percent at 0821 GMT.

Some Wavefield shareholders believe TGS knew it had missed market estimates of third-quarter earnings when voting for the merger in September.

TGS-Nopec said a review it ordered from PriceWaterhouseCoopers showed that TGS could not tell its third quarter would be weak by the Sept. 20 Wavefield shareholders meeting that approved the merger.