Downer EDI boss Peter Tompkins is confident the competition watchdog’s investigation into alleged price fixing of defence contracts will not hurt its chances of winning big contracts with the federal government as he tries to stabilise the engineering group.

The group, which reported a 5 per cent rise in interim net profit to $75.5 million, expects to hear by June whether it has been successful in renewing a multi-billion dollar contract to provide maintenance and operational services to 170 defence sites in three states.