* Q3 EBITA 105 mln euros vs Rtrs poll avg 99 mln
* Reiterates 2012 outlook
* Shares rise 6 pct, MDAX down 0.2 pct, peers down 0.8 pct (Adds CEO comments on outlook, compliance, updates shares)
FRANKFURT, Nov 14 (Reuters) - Germany's Bilfinger beat expectations for quarterly earnings, helped by orders to maintain factories in Scandinavia, oil platforms in the North Sea and a gas plant in Germany.
Bilfinger, which services industrial plants, won major orders in the period from clients such as Germany's BASF , Britain's BP and Norway's Statoil, the Mannheim, Germany-based company said on Wednesday.
But Chief Executive Roland Koch, a former premier of the German state of Hesse for the conservative CDU party, warned the economic environment was becoming increasingly difficult, making it harder to reach the company's targets for 2016.
"The path to increase margins in the industrial's unit is steeper than expected," he said in a telephone conference, referring to the business division that generates the largest share of earnings.
Bilfinger aims to double net income to 400 million euros in 2016 and raise EBITA to 700 million, and Koch told Reuters in an interview in August that profits will rise continuously in the period.
Earnings before interest, tax and amortisation (EBITA) for the three months through September w e re f lat from a year earlier at 105 million euros ($133 million), beating a consensus of 99 million euros in a Reuters poll.
The shares rose 6 percent, the biggest increase in more than a year, while the German mid-cap index fell 0.2 percent and peers on the STOXX Europe 600 Construction & Materials index , dropped 0.8 percent.
Koch said he still aimed to post 2012 EBITA of 450-470 million euros and a net profit of 265-275 million euros, but declined to comment on 2013.
Bilfinger still has about 1 billion euros to invest in acquisitions after spending about 500 million euros on takeovers, including Dutch project planner Tebodin, a spokesman said on Wednesday.
The results come as Bilfinger faces a regulatory investigation, with media reporting irregularities in relation to winning an order to build a highway in Hungary and a metro in Budapest and Bratislava.
Prosecutors in mid-October raided several of Bilfinger's offices because of unspecified incidents in the years 2006 and 2007, but Bilfinger has declined to provide details.
Koch said on Wednesday that the two employees concerned were put on leave during the investigation and that he saw no systemic violation of the company's compliance rules.
(Additional reporting by Tom Atkins. Editing by Louise Heavens)