Construction jobs are at risk because of the absence of devolved government in Northern Ireland, according to the Construction Employers’ Federation.
Public spending on infrastructure projects makes up an important part of workloads for construction firms.
Without it, bosses are concerned they are going to have to lay off staff.
The CEF said some projects have already been stalled, including the Belfast Streets Ahead project that was due to start this year.
CEF’s managing director, John Armstrong, said: “Unless we have an executive in place making decisions, we’re going to see job losses and I think that’s coming quite quickly now.”
He added: “Construction companies can’t just wait in limbo, they are employing people and if the projects don’t come along then people will be laid off.
“I certainly have had member companies say to us that it’s not worth working in Northern Ireland and they are going to look elsewhere now.”
The Belfast Streets Ahead project is a multi-million pound scheme to improve the area from Castle Place to the new Ulster University campus on York Street.
A Department for Communities spokesperson said the procurement process was discontinued in August, with no contract awarded.
They said: “This is because there was no previous and explicit executive or ministerial endorsement for the project and also, crucially, because the department had not been allocated any money to spend in future financial years on any capital project that did not have previous and explicit executive approval.”