Southampton have signed Stuart Armstrong from Scottish champions Celtic on a four-year deal, the English Premier League club announced on Tuesday.

No fee was disclosed by the Saints but British media reported that Scotland midfielder Armstrong had joined the south coast side for a figure in the region of £7 million ($9.25 million, 8 million euros).

Armstrong's future at Parkhead had been uncertain ever since talks regarding a new contract with the Glasgow giants had faltered and Celtic now appear to have decided it is better to offload Armstrong now and not run the risk of him leaving for nothing when his current deal expires in a year's time.

Formerly with Dundee United, Armstrong was a member of the Celtic side rhat recently completed a 'double treble' under manager Brendan Rodgers.

In total, Armstrong won eight major trophies during his time with Celtic.

He scored 17 goals during the 2016/17 season and gained a place in the Scotland set-up but endured a frustrating time last term with injuries.

Armstrong is Southampton's first pre-season signing after they narrowly avoided relegation from English football's top-flight

Southampton only scored 37 league goals last season and manager Mark Hughes hopes Armstrong can bolster their attack.

"Stuart is a player who we have admired for some time, and I am delighted we have been able to bring him here, especially given the competition we faced to sign him," Hughes told Southampton's website.

"We have strong players in the squad and it is important we build on that by adding different qualities.

"It is important we add a greater goal threat to the team as a whole, and to our midfield specifically, and Stuart's record of scoring and creating makes him an extremely exciting addition in that area," former Manchester United and Wales striker Hughes added.

"He brings with him extensive experience of European football and has developed his game impressively over the past few seasons at a major club in Celtic, where there is a demand not only to perform but also to win."

Meanwhile Armstrong said: "Southampton seems a really good fit for me. Watching from afar, I really enjoy the attractive football that they play and I'm very happy to be here.

"Every season, I put demands on myself to create and score goals. I hope going forwards from here that it will be the same this term at St Mary's."