"Team" of companies?

When several people work together, we call them a team.

When companies work together, we call them a ____?

They are not a group, as that signifies a permanent relationship. What is a temporary "team" of companies called that only work together on one project? I think there is a term, but cannot remember it.

I'd definitely opt for consortium

Noun Plural: consortia

Group of people, companies, etc., that agree to work together

(Merriam-Webster)

This is also the word used by the UK Government to describe a group of companies involved in, for example their Private Finance Initiative - basically big companies build schools, hospitals etc. for the government.

The use of the word "partner" in the context of two or more companies associating with one another is now very common and one often sees some reference to our "Partner Companies" in corporate writing. This merely announces an association or cooperation that is not covered by Partnership Law in the UK, for example. Company Law is mutually exclusive. To use the word Partnership would express or imply the legal status of a "Partnership" but not that of a Company. To use the word partner company has no such legal implication of a partnership under UK law.

(Lindley & Banks on Partnership)

joint venture

A joint venture (JV) is a business arrangement in which two or more parties agree to pool their resources for the purpose of accomplishing a specific task... However, the venture is its own entity, separate and apart from the participants' other business interests.

• From Investopedia

industry cluster or business cluster

A business cluster is a geographic concentration of interconnected businesses, suppliers, and associated institutions in a particular field. Clusters are considered to increase the productivity with which companies can compete, nationally and globally.

• From Wikipedia

The answer by @BladorthinTheGrey is correct. I would also volunteer corporate group in the case where the companies are controlled by a common source.

Definition:

A corporate group or group of companies is a collection of parent and subsidiary corporations that function as a single economic entity through a common source of control.

Source: Wikipedia