* Elliott holds 6.8 pct stake - regulatory filing
* Position taken day after SNC Lavalin agreed to buy WS Atkins
* Elliott declines to comment on move (Adds background, context, Elliott 'no-comment', share price, bullet points)
By Vikram Subhedar and Simon Jessop
LONDON, April 24 (Reuters) - U.S. activist investor Elliott Capital Advisors disclosed on Monday it has taken a 6.8 percent stake in WS Atkins ATKW.L after the British engineering and construction consultancy firm agreed to be bought in a C$3.6 billion ($2.7 billion) deal.
Elliott said in a regulatory filing that it had acquired the stake in a contracts-for-difference deal on April 21, the day after Atkins agreed to its acquisition by Canadian construction and engineering group SNC Lavalin SNC.TO . in Atkins last traded on Monday at 2,100 pence a share, above SNC's offer price of 2,080 pence.
After SNC made an indicative offer for Atkins on April 3, Liberum analyst Joe Brent told clients in a note the move could spark a bidding war, given growing consolidation in the industry. He declined to comment on Monday.
The move on Atkins opens up another front in Europe for Elliott, as it presses Dutch-based paintmaker Akzo Nobel AKZO.AS to open takeover talks with U.S. suitor PPG Industries (NYSE:PPG) PPG.N , and separately campaigns for a restructuring at Anglo-Australian miner BHP Billiton BLT.L BHP.AX . stake in Atkins makes it the second-biggest shareholder, Thomson Reuters data showed, just behind asset manager Columbia Threadneedle.
A spokeswoman for Elliott declined to comment on why the firm had taken a stake in Atkins. A spokesman for Atkins also declined to comment, while no one at SNC-Lavalin could immediately be reached for comment.
($1 = 1.3482 Canadian dollars)