UPDATE 2-Norwegian seismic tie-up takes nasty tone

(Combines separates, adds details, closing share prices)

By John Acher and Wojciech Moskwa

OSLO, Dec 7 (Reuters) - A row over Norwegian seismic surveyor TGS-Nopec's (TGS.OL: Quote, Profile, Research) $1.2 billion takeover of peer Wavefield Inseis (WAVE.O: Quote, Profile, Research) deepened on Friday, hitting the valuations of both firms.

TGS-Nopec said it launched a formal process to resolve a dispute over the all-share deal, which was put on ice by Wavefield last month after an unexpected profit warning by TGS knocked the value of the deal to Wavefield shareholders.

Wavefield hit back on Friday, blasting TGS as "unfriendly" and uncooperative, further eroding expectations for a deal. Wavefield also refused to participate in a TGS-led project in the Gulf of Mexico.

"TGS initiates the procedure with the aim to close the merger as the current stagnation of the merger process is deemed unfortunate both for the merging parties, their employees and for their shareholders," TGS-Nopec said in a statement.

In response, Wavefield said: "Today's press releases from TGS-Nopec, and general approach to solving this merger issue is now considered to be unfriendly."

"TGS-Nopec has repeatedly demonstrated a lack of willingness to cooperate with their merger partner's reasonable requests for information," Wavefield said.

Wavefield shares slid 3.8 percent to 40.90 crowns, and TGS shares dropped 4.0 percent to 69.10 on Friday, underperforming a 1.6 percent fall in the Oslo bourse benchmark index .