A new "support unit" established inside the Department of Agriculture to advise Deputy Prime Minister Barnaby Joyce on issues outside his portfolio has been mocked as "political training wheels" by Labor.

An internal departmental alert obtained by Fairfax Media announces the formation of the "Deputy Prime Minister Support Unit".

"In his role the Deputy Prime Minister is expected to respond to issues beyond the agriculture and water resources portfolio. For example, he may be asked about immigration or transport which do not fall within our department's area of responsibility, but he will nevertheless provide an answer," the memo states.

"The Deputy Prime Minister Support Unit's role is to assist Minister Joyce by looking at the 'big picture' and forming strategic links within the department and across government to respond to whole-of-government policy issues and broader government initiatives. In practical terms, it will review submissions, prepare or contribute to briefs, organise correspondence and provide input to talking points."