Former deputy Prime Minister Barnaby Joyce and Vikki Campion welcome their baby boy.

Barnaby Joyce and his partner Vikki Campion have reportedly welcomed their baby boy, Sebastian, weighing in at eight pounds and seven ounces.

It is believed their son was born on Monday.

He is the fifth child and first son for the former Deputy Prime Minister, and first child for Ms Campion.

Mr Joyce lost his cabinet position and the Nationals leadership after it was revealed he and Ms Campion, his former media adviser, were expecting a child.

Prime Minister Malcolm Turnbull later introduced a ban on ministers having sexual relations with their staff.