The company A (client company) needs to add more people than they have to their workforce in order to get a project done, so they make an agreement with a company B (consultancy, temporary employment agency, etc) that provides the extra people they don't have.
Those contractors from the company B work alongside other people at the company A, doing the same tasks and under the same premises, but they have a contract with the company B so they are not employees of A.
How do you call such people? I think the word in English is contractor. I have looked up its Japanese translation in dictionaries and they translate it as 業者. However it seems to be related to jobs like traders or real estate agents, so I'm not sure it is the word I'm looking for. Is 業者 the right term to label the people described in the scenario above (regardless of the industry) or there is a more appropriate term?