Across the international group, operation profits more than doubled to £13m and revenue rose 13% to £614m in the six months to June.
As a result group-wide operating margins have crept up to 2.2% from 1.3% last year.
Justin Atkinson, Keller Chief Executive said: “These results show a strong improvement overall, with three out of four of the group’s regions performing significantly better than at this time last year.
“In addition to the usual seasonal improvement, a recent stepping up of production on several of our major projects will help to support a stronger second half.
“Accordingly, the group’s results for the full year are expected to be slightly ahead of the top end of the range of market expectations.
“However, there remains much uncertainty around the macroeconomic outlook and conditions in our construction markets around the world continue to be mixed.”