The acquisition is expected to be completed later this year, subject to anti-trust approval. The co-founders of Hector Rail will stay on, with Mr Mats Nyblom continuing as CEO and Mr Ole Kjörrefjord becoming a board member. Mr Bo Lerenius, EQT's industrial advisor, is expected to be appointed chairman of Hector Rail.

Hector Rail was set up in 2004 with the backing of the Norwegian Høegh family. The company has 190 employees and operates a fleet of 50 locomotives and 10 shunters. It operates around 6 million train-km a year and had a turnover of SKr 630m ($US 92.3m) in 2013.

"Hector Rail is a well-run business with a strong track record and excellent reputation," says Mr Stefan Glevén, partner at EQT Partners. "We are convinced that rail transport will gain market share."

"With EQT Infrastructure II as a new owner, we will continue to build on our successful business model and growth plan," Nyblom adds.