The system is designed to give government department agencies (GDAs) electronic contact with their suppliers.
The site will be open to all suppliers, from IT and stationery to travel and healthcare.
Cap Gemini Ernst & Young, Elcom and Cataloga have formed a consortium to run the system, after winning a seven-year contract in November.
Elcom managing director Michael Templeman revealed it had become involved in an early stage of the bidding process, but teamed up with its partners Cap Gemini and Cataloga after the first round of approval, with Cap Gemini running the bid.
Elcom provided the e-procurement software and services technology, Cap Gemini handled the consultancy and Cataloga ran the content management.
Most GDAs currently place orders on paper, but the aim of the e-procurement system is to get all 100 online.
"When a GDA gets involved with the initiative, we will get in touch with its suppliers and put their catalogues online with the specific prices for that customer," Templeman said.
"If the supplier does not have Internet access, we can automatically print out any order and fax it to them."
The site would also warn a GDA if it was trying to spend over budget and automatically inform the person in charge of approving any purchases, he added.
Only three GDAs have signed up to the initiative so far, but Templeman was confident the number would increase and the system would be used as a template for other government procurement plans.