Vaas has taken 11 five-wicket Test hauls since his debut in 1994

John Emburey's side were relegated from both the Championship and Pro40 and will welcome 32-year-old Vaas, who has taken 307 Test and 354 one-day wickets.

It is also believed that India spinner Murali Kartik, who has also played for Lancashire, is in talks with the club.

No decision has been yet made on Ben Hutton's replacement as captain, while Chad Keegan is considering a new deal.

Also confirmed at the Middlesex annual general meeting were the departures of Melvyn Betts for health reasons, New Zealander Scott Styris, Johann Louw and Mohammad Ali.

Former Essex and England left-arm seamer John Lever will be the club's new fast bowling coach.

Playing for Middlesex is very special because I know it is a very fine club Chaminda Vaas

Vaas spoke of his delight at joining his third English county, having previously played for Hampshire and Worcestershire.

"I am delighted with the offer," he said. "I have always enjoyed the county scene, and playing for Middlesex is also very special because I know it is a very fine club."

"I am looking forward to a very competitive and enjoyable summer of cricket."

Middlesex chief executive Vinny Codrington said of his club's new acquisition: "He is a world-class player who Sri Lanka have very kindly made available to us for next season.

"His bowling is ideally suited to the Lord's wickets and he's proved himself not only as a world-class bowler but also as a useful lower order batsman.

"We are thrilled he's joining us."

It was rumoured that another Sri Lankan star, Sanath Jayasuriya, was being lined up to skipper Middlesex next season but this has been dismissed.

"That is pure speculation," a county spokesman insisted.