Full year revenues in Europe - down 3% in the latest quarter - were likely to be similar to the previous year, said Aggreko, while demand in North America was "holding up better than we expected".
The company, it its trading statement for the three months to 30 September, said it expected its full-year performance to exceed market expectations, with profits before tax likely to be 50% higher than last year.
Rental sales rose 10% in North America and by a remarkable 59% in the Middle East, Asia Pacific and Central/South America, helped by US$22 million revenues from the Beijing Olympics.
Total group revenues, adjusted for currency changes, were up 30%, with the group's International Power Projects division reporting a 54% increase, benefitting from projects initiated in the first half of the year becoming fully operational. Sales in North America were boosted by rentals related to Hurricanes Gustav and Ike.
Aggreko said; "Momentum remains very strong in Aggreko International, with our local businesses in the Middle East, Asia, and Central & South America all expected to make further strong progress throughout the remainder of the second half, helped in part by a very rapid redeployment of the fleet used to support the Beijing Olympics."
Meanwhile, long-time Aggreko executive Derek Shepherd will retire from Aggreko at the AGM in April 2009. Mr Shepherd has been responsible for Aggreko International for the past 10 years, during which its revenues have grown from £35 million to over £500 million.
He will be succeeded by Kash Pandya, who joined the Aggreko's board in 2005 and who led the turnaround in the performance of Aggreko's European business.
At the same time, Aggreko will merge its rapidly growing local rental business in the Middle East, previously part of Aggreko International, with its European local business, to create a Europe & Middle East region. That new enlarged region will be managed by Bill Caplan, who joins Aggreko as regional director, Europe & Middle East. He will also be an executive director at the company.
Mr Caplan, born and educated in the US, has spent the last 18 years working for United Parcel Service (UPS) in Pittsburgh, London, Shanghai and Singapore.
Rupert Soames, Aggreko's chief executive, said; "We are delighted that Bill will be joining Aggreko, and to see Kash moving to run our largest and fastest-growing business. The merging of our Middle East and European businesses will create a local business with improved scale, and will equip us better to build our presence in developing markets across the region.
"It will also enable Aggreko International to focus on International Power Projects and on developing its key markets in Asia-Pacific, Africa and Central & South America."