Defenceman Robyn Regehr has agreed to a trade from Calgary to Buffalo after much consideration.

Robyn Regehr is leaving the Calgary Flames after more than 11 seasons, heading to Buffalo in a multi-player deal officially confirmed on Saturday.

Calgary will also send veteran forward Ales Kotalik and a second round pick in 2012 to the Sabres, getting defenceman Chris Butler and prospect Paul Byron, a centre, in return.

Regehr, 31, needed to sign off on the move per the terms of his contract. The rugged defenceman played 827 regular season games with the Flames, compiling 29 goals and 134 assists with 802 penalty minutes.

"[Asking a player to waive a no-trade] is the toughest thing that you do," general manager Jay Feaster said. "I went through it in Tampa with Brad Richards and there was a guy that won a Stanley Cup for us.

"When you have a warrior like Robyn is, a guy who has been there as long as he's been there and has done as much for the franchise as he has, that's a very, very difficult phone call to make."

Providing a steady presence on the blue-line, Regehr has missed on average just four games per season over the past decade of play. There will be at least one familiar face for him the returning Sabres — former Flames defender Jordan Leopold.

Kotalik is returning to the club where he enjoyed his greatest success. Since leaving the Sabres in a 2008-09 deal, he's failed to last long with Edmonton, the New York Rangers and the Flames.

The situation got so bad in Calgary for Kotalik that he even spent time in the American Hockey League.

The 32-year-old Czech Republic native has scored 136 goals and added 148 assists in 542 career games.

Butler has played 155 games in three seasons with the Buffalo Sabres, with five goals and 31 assists and a plus-4 rating.

Byron is a skilled but small centre who spent most of his first pro season with Portland of the American Hockey League. The five-foot-nine Ottawa native got in eight games of NHL action with Buffalo, with a goal and an assist.

The Regehr deal leaves just captain Jarome Iginla and goalie Miikka Kiprusoff from the Calgary team that reached the seventh game of the 2004 Stanley Cup Final.

The transaction makes some much-needed room for the Flames with respect to their salary cap situation.

Regehr represents a cap hit of just over $4 million US the next two seasons. Kotalik is to earn $3 million next season.

The 25-year-old Butler is a restricted free agent who earned $585,000 last season.

"We've been in salary cap jail for some time," Feaster said. "This gives us an opportunity to have some breathing room and have a fresh start and at the same time to get younger."

The Flames soon after the trade announced a new contract for forward Alex Tanguay, valued at $17.5 million over five years. He was due to become an unrestricted free agent next week.

Tanguay, 32, rebounded after a couple of subpar seasons with 22 goals and 47 assists in his second stint with Calgary. He earned a career high of 81 points with the Flames in 2006-07 before eventually departing for stops with the Montreal Canadiens and the Tampa Bay Lightning.

In an NHL career that began with six seasons with Colorado, he has scored 225 goals and 460 assists in 817 regular season games with 401 penalty minutes. He won a Stanley Cup with the Avalanche in 2001.

"As we looked at the potential (unrestricted free agent) market, we didn't see a player that was going to replace him and be as productive as we believe he can and will be," Feaster said. "We're happy to have him back. The earlier transaction put us in a situation where we actually able to get that done today and get it filed."

On Day 2 of the draft the Flames selected Finnish centre Markus Granlund with the 45th pick in the draft before adding defenceman Tyler Wotherspoon of the Western Hockey League's Portland Winterhawks at No. 57.

Granlund is the younger brother of Minnesota Wild prospect Mikael Granlund.

Wotherspoon, a six-foot-two defenceman from Surrey, B.C., had two goals and 10 assists in 64 WHL games last season.

The Flames also added left-winger John Gaudreau of Dubuque of the USHL in the fourth round at No. 104 and Edmonton Oil Kings defenceman Laurent Brossoit in the sixth round at No. 164.