“I’m delighted. It was a very easy decision to join this club,” he told Southampton’s official website.“This is a very ambitious club, who have been doing very well in the last couple of years. It’s a great place to be and it’s the right step for me.

“For me now to get the opportunity to play in the Premier League is unbelievable and I will enjoy it.

“I know it’s an ambitious club – they have been through a lot throughout the years. They are trying to play football and that’s something that really attracted me.

“I’m so excited. I hope to settle in really quick, get everything around football sorted, start playing and enjoying it because the most important thing in football is to have fun and enjoy every day.”

Celtic have also confirmed that Inverness CT attacker Ryan Christie has joined the club on a four-year deal. Christie will be loaned back to the Highlanders.