Barnaby Joyce says he will push the bosses of milk giant Murray Goulburn to return money to dairy farmers during talks with him and Prime Minister Malcolm Turnbull on Tuesday.

The government announced an assistance package for dairy farmers during the federal election campaign, but it was revealed this week only one concessional loan has been approved as part of the package.

Retrospective price cuts by Murray Goulburn have led to demands for milk producers to pay thousands back to the co-operative, while on Monday ABC TV revealed emails to senior executives showing Murray Goulburn was making significant losses before it decided to downgrade milk prices.

Mr Joyce said the government would require transparency from the company but denied he would act as "solicitor or the policeman".