The 18-year-old became the youngest Orlando Pirates player to score an official goal with a strike against Polokwane City last season at the age of 17 years, four months and 16 days.

He immediately joins the French side's reserves and Foster says the move gives him the chance to move closer to his "dream."

"A very exciting start to the new year. I would like to thank Orlando Pirates for giving me the opportunity to start my professional career, my trainer club, the club that moulded me into the man I am today," Foster wrote on his personal instagram page.

"To be at the club since age of 12 is something I'm really proud of and I will always be grateful to Orlando Pirates.

"I'm ready to take this new step in my career and be a little closer to my dream with Monaco. I'm grateful for the opportunity and ready to fight for my dream," Foster wrote.

Pirates' Head of Youth Development, Augusto Palacios, is thrilled to see one of the club's youngsters moving to Europe.

"It is such an honour to see Lyle moving to a big club at such a young age. As a person who is passionate about youth development, this is the type of thing that makes the long hours all worth it," he told the club's official website.

The Soweto-born forward scored once in 11 professional appearances for Orlando Pirates after earning promotion to the senior squad.

He has represented South Africa at the Under-17 and U-20 levels.

Foster finished as joint-top scorer with five goals to help his country to the regional Council of Football Federations of Southern Africa (Cosafa) U-20 championship title in December.