* Q2 net loss 15 mln eur vs Rtrs poll avg of net profit of 73 mln eur
* Says net loss due to provisions for Elbphilharmonie project
* Reiterates expectations for FY net profit, pretax profit
* Would have to beat H2 earnings of last 5 years to reach target
* Shares down 2 pct, peers down 0.2 pct (Adds Reuters calculations, analyst comments)
FRANKFURT, Aug 14 (Reuters) - Hochtief, the German construction and industrial services provider controlled by Spain's ACS, reported a surprise second-quarter loss on Tuesday, hit by a troubled concert hall project in Hamburg which analysts said now puts the company in danger of missing its full-year profit forecast.
The company would have to earn about 475 million euros ($587 million) before taxes and about 229 million euros net in the second half to reach its targets.
That is more than the company has earned in each second half of the last five years, according to Reuters calculations.
"It will be really difficult to reach the full-year target," said Bankhaus Lampe analyst Marc Gabriel.
The shares were down 2 percent at 0845 GMT, underperforming a 0.2 percent drop of the STOXX Europe 600 Construction & Materials index.
Chief Executive Frank Stieler reaffirmed on Tuesday he still expected the company to make a pretax profit of just under 550 million euros ($679 million) and a net profit of just under 180 million euros in 2012 despite reporting a disappointing net loss of 15 million euros in the second quarter.
Analysts in a Reuters poll had forecast a net profit of 73.1 million euros for the quarter.
For the full year, the sale of its stake in a Chilean toll road would help offset as yet unspecified provisions made on the Elbphilharmonie concert hall and flats development in Hamburg, the reason for the second-quarter loss, Stieler said.
But he admitted it would be more difficult to reach that target, a comment some saw as indicating the profit outlook would have to be cut.
"The company might have to lower its guidance," said DZ Bank analyst Marc Nettelbeck. "Low utilisation rates in Europe and the Americas show me that their other business is not going too well either."
Before Tuesday's statement, the analysts in the Reuters poll on average had expected Hochtief to even beat its targets.
The Elbphilharmonie development has turned out to be a costly project for Hochtief due to disputes with the city of Hamburg over construction delays.
Hamburg has sued Hochtief for damages for the delays but the group has not disclosed how much it has had to set aside in provisions. A spokesman said Hochtief would not release the figure so as not to compromise its negotiating position in continuing negotiations.
The Chilean toll road, which is meant to make up for the provisions, was sold for 230 million euros.
Despite the quarrels in Hamburg Hochtief is winning more business than it previously forecast. It now sees the intake of new orders running flat this year compared with 2011 after previously forecasting a decline.
Parent company ACS said last week it returned to profit in the first half and expects to achieve its full-year profit outlook. ($1=0.8096 euros) (Editing by Maria Sheahan and Greg Mahlich)