Fairfax Media can reveal Giteau emerged as a genuine recruitment target for the Brumbies to help fill the void left by Christian Lealiifano and Matt Toomua.

It was hoped the club could strike a deal to have Giteau for at least some part of the season, but the Super Rugby title winner's deal with French giant Toulon will make it almost impossible for him to join the Brumbies.

News of the Brumbies' bold bid for Giteau follows the NSW Waratahs attempts to sign his Toulon teammate Drew Mitchell for a Super Rugby comeback.

Giteau spent some time in Canberra recently recovering from injury but has returned to France to resume his duties with one of the richest clubs in the world.

Giteau signed a two-year deal with with an option for a third season in 2014 to stay with Toulon and at the time said: "Very happy I will finish my career here."

However the 34-year-old, 103 Test veteran proved at the World Cup last year he still has what it takes to match the best in the world and could slot back into Super Rugby.

His presence in Canberra would have been a massive boost for the Brumbies with Lealiifano unlikely to play any role next year as he continues his treatment for leukaemia.

He would have also added valuable leadership as the Brumbies prepare to find a new captain following Lealiifano's illness and the departure of Stephen Moore.

Giteau played in the Brumbies' championship-winning side in 2004 and was the club's captain in 2011. He left Australian rugby in 2011 and has since tasted European success with Toulon.

Brumbies officials made initial approaches to gauge Giteau's interest in a shock comeback and were prepared to investigate options, but it's understood he is committed to finish his deal with Toulon.

The Brumbies have two days of training left before the players are given leave for the Christmas break. They will return on January 5 and coach Stephen Larkham will appoint a captain before their first game in February.

Eight players have stepped up in leadership roles in the first pre-season training block with the squad's Wallabies contingent away on international duties.

Respected back-rower Jarrad Butler is regarded as a future leader and has been in charge of the Canberra Vikings' National Rugby Championship side.

"If I got the opportunity [to captain the Brumbies], that would be awesome and I'd relish it," Butler said.

"But we haven't spoken about that at all and it's definitely not something that I've even thought about. There are so many guys that I think would do a really good job in that position.

"I'm really glad to be in the pre-season leadership group and learn from there every week that we go through."

Butler has spent the majority of the pre-season training at openside flanker as the Brumbies also try to fill the sizeable hole left by David Pocock, who has taken a sabbatical from Australian rugby.

Butler has previously filled the No. 7 duties and will compete with Chris Alcock for a starting spot.

"There's always going to be competition and the back row is always highly competitive," Butler said.

"It's exciting and I think it's really good for the back row, but will then help the entire team. I've been training mostly at No. 7 at the moment so that's what I'm working on now.

"But I haven't spoken to the coaches if they want me to be versatile or lock down something else. So I'll just try to get better at it all every week."