Updated April 20, 2018 15:37:49

Photo: Barnaby Joyce announced he was expecting a baby with Vikki Campion earlier this year. (ABC News: Lucy Barbour)

Former deputy prime minister Barnaby Joyce and his partner Vikki Campion have welcomed a baby boy, named Sebastian.

He was born at Armidale public hospital on Monday this week, weighing 3.8 kilograms.

Mr Joyce quit as Nationals leader and deputy PM in February amid pressure over his relationship with Ms Campion, his former staffer, and the news of her pregnancy.

Mr Joyce almost shares a birthday with Sebastian — he turned 51 on Tuesday, the day after the baby was born.

Mr Joyce has four daughters with his wife Natalie. Sebastian is Ms Campion's first child.

Last month, Mr Joyce told the media the paternity of his partner's then-unborn child was a "grey area", but said he was planning to raise the child as his own regardless of who the father was.

The couple's affair raised questions about whether the statement of ministerial standards was properly followed, when it emerged Ms Campion moved from a media adviser's position in Mr Joyce's office to a job with his Nationals colleague, Matt Canavan.

It also prompted Prime Minister Malcolm Turnbull to ban sex between ministers and their staffers.

More to come.

Topics: government-and-politics, joyce-barnaby, australia

First posted April 20, 2018 15:00:32