More than £1bn of infrastructure projects are at risk because of stalemate at Stormont, according to the Institute of Directors.
At a meeting on Thursday the group told the NI Secretary of State that the status quo was "unacceptable".
Kirsty McManus, director of the Institute of Directors (IoD), described the meeting with Karen Bradley as "robust".
Her comments followed the blocking of a controversial incinerator in Mallusk.
Mrs McManus said: "This week's legal ruling on the energy from waste plant at Mallusk, has put at risk more than one billion pounds of strategic infrastructure projects and cast doubt over billions of pounds worth of projects still in the pipeline across the public and private sector.
"A lot of our members are extremely anxious around key infrastructure projects such as the north-south interconnector, the Belfast power station.
"We are really concerned that we are now in the vacuum where no one can make decisions."
Earlier on Thursday the secretary of state said she was "aware of concerns" over what decisions departments can make in the absence of ministers.
The head of the civil service, David Sterling, has previously said there is a lack of clarity on the issue of decision making in the absence of ministers.
Mr Sterling had also warned that events such as the North West 200 could now be at risk.