* H1 trading profit rises to 107.0 mln pounds
* H1 revenue up 5 pct in constant currency, excluding fuel
* Full-year outlook unchanged
* Shares up 1.5 pct (Adds chief executive comments, reaction, shares)
By Paul Sandle
LONDON, Aug 25 (Reuters) - Britain's Aggreko Plc, one of the world's largest providers of temporary power sources, posted a 14 percent rise in first-half trading profit, and said its full-year outlook was unchanged with profit on a constant currency basis expected to be similar to 2008.
Aggreko, which powered this month's World Athletics Championships in Berlin and the Beijing Olympics in 2008, reported trading profit of 107.0 million pounds ($176.6 million), up 46 percent as reported, but 14 percent higher in constant currency.
Revenue, excluding fuel and in constant currency terms, grew 5 percent to 474.8 million pounds, it said, while pretax profit increased 56 percent to 105.7 million pounds.
Both trading profit and revenue were broadly in line with the company's outlook in June, when it said growth in international power projects (IPP) was offsetting weakness in short-term local rentals.
Analysts expected the group to report adjusted pretax profit of 210 million pounds for the year, up from 190.2 million pounds in 2008, according a Reuters poll of 13 brokers.
Chief Executive Rupert Soames said he was expecting a tough second-half, reflecting weaker demand for temporary power against a year ago, when rentals were boosted by storms in the United States and by the Olympics.
"Conditions have got a lot tougher in the local business," he said in an interview on Tuesday.
"In Q2 conditions deteriorated in the market, and that's continued into Q3; that's not got any worse but conditions are not nearly as good as it was a year ago."
Soames said there were some bright spots, such as the Middle East, and although rates had fallen it had probably gained market share.
"Revenue in local business in Q3 I expect will be 20 to 25 percent below where they were last year, that compares to 13 percent down in constant currency in the first half," he said.
Demand for temporary air conditioning was also down, as firms did not need to cool factories idle in the summer months, and the weather was more benign.
But the group was still seeing growth in its International Power division, which supplies large power capacity, mainly in developing countries, and recently signed a 140MW deal in Kenya .
"It gave people some cheer that there were deals around for large amounts of power and we were winning them," Soames said.
"There are fewer of these large deals than before. We have a strong enquiry pipeline but the deals we are closing are for a shorter duration and for a smaller number of megawatts."
Shares in the group, which have rallied since touching a three-month low of 476.25 pence after the June update, were 1.5 percent higher at 623 pence by 0847 GMT, outperforming a 0.5 percent weaker index of medium-sized companies.
Cazenove, which has an "in-line" recommendation on the stock, said they would increase their adjusted pretax profit forecast by 5 percent to 220 million pounds, principally for currency.
"A good set of numbers, in line with expectations with pressure on the local businesses as expected (particularly temperature control) being offset by a strong performance from IPP," they said in a note.
Aggreko increased its interim dividend by 15 percent to 4.37 pence a share. (Editing by Julie Crust)
($1=.6059 Pound)