Leighton Holdings says it won't bid for work on massive gas projects like Gorgon until it can secure workers amid labour shortages, rising wages and increased union activity.
Chief executive David Stewart said there had been delays on the liquified natural gas (LNG) project, but the federal government's migration and industrial policies were making life difficult for contractors in resource hotspots.
"Labour is critical," he told analysts after Leighton released its full year results on Monday.
"We won't bid (for) projects where there is a labour risk that we can't manage.
"If someone wants 2,000 people in three months at some location, we can't commit to that because I don't know where I'm going to get them from."
Mr Stewart said skilled migration had worked well to supply infrastructure projects in the past, dating as far back as the Snowy Mountains scheme.
"The government keeps the doors shut. They won't have a migration policy that will allow people to come in," he said.
"It would seem that at the moment when Australia has got the best opportunity to capitalise on (liquified natural) gas and minerals wealth that we have, that we're going to be constrained by labour.
"That is our biggest single constraint and we won't take the risk."
Leighton reported a full year loss of $408.8 million for the 12 months to June 30, down from a $612 million profit a year earlier, but reiterated a net profit forecast for financial 2012 of $600 million to $650 million.
Mr Stewart said Leighton and its subsidiary Thiess were still "engaging strongly" on the Gorgon projects and were in a "very good position".
He foreshadowed potential problems as Gorgon dealt with native title and environmental issues, but said one of his greatest fears was the federal government had "let the unions back into the room".
"We're seeing productivity declining significantly on our construction projects over the last three years," he said.
Unions were now demanding more money and blue collar workers were making "more money than they've ever made before," he said.
City Index analyst Peter Esho said Leighton's "constant warning" of labour costs and capacity constraints was the most important thing to take away from Monday's result.
