Australian actor Guy Pearce and partner, Game of Thrones star Carice van Houten, have welcomed a baby son.

Pearce announced the news on Twitter, including the bizarre offer of a “placenta smoothie”.

“A cute little package arrived and told us his name’s Monte Pearce,” Pearce posted.

“We think we’re gonna keep him. Placenta smoothie anyone?”

A cute little package arrived and told us his name's Monte Pearce. We think we're gonna keep him. Placenta smoothie anyone? @caricevhouten

— Guy Pearce (@TheGuyPearce) August 29, 2016

Van Houten is best known for playing the witch Melisandre on the wildly popular series Game of Thrones.

It is the first child for Pearce, 48, and van Houten, 39, who have been together since last year.

A spokesperson for van Houten, who is from the Netherlands, confirmed the baby was born last week in Amsterdam.

Pearce married his childhood sweetheart Kate Mestitz in 1997, but announced in October last year that the couple had split after 18 years of marriage.