GEORGE BOATENG'S future remains uncertain but Middlesbrough manager Gareth Southgate insists the Dutch midfielder has grown more accustomed to his captaincy role as time has gone on.

Birmingham City are understood to be interested in taking Boateng back to the Midlands, where he made a name for himself in English football with Aston Villa and Coventry.

Despite improvements in form as last season developed, the 31-year-old failed to hit the heights he had managed in his previous four years on Teesside, which has contributed to the speculation about his future.

The emergence of Lee Cattermole, an Academy product in the Boateng mould who has been forced to play regularly out wide, has also led to demands for the teenager to be given an opportunity to impress in the middle.

A previous interest in Manchester City's Joey Barton highlights how Middlesbrough are looking to bring a fresh face in during the next couple of months, and that has been further reflected by a monitoring of Fulham's Hartlepool-born Michael Brown.

But Southgate, a former team-mate of Boateng at Villa and Boro, thinks his club skipper still has plenty to offer in the top-flight, even if a change of position may be the best way forward.

"Towards the end of the season we played George back in the position he used to play for Coventry, when he first came over here, and he has been playing very well," said Southgate, who tried the two-time Holland international as a right-back and right-midfielder.

"He suffered earlier in the year injury wise, and is the type of character who wants to keep playing and performing for the team. It was a big change for him taking on the captaincy. He wanted to succeed and that can have an effect on you.

"He is a very proud man and he wanted it to work out in the right way. He matured into the role and got stronger. He will be the first to admit he didn't reach the levels he has in previous seasons here.

"But he showed in certain games what a big player he is for us and statistically he is still right up there in terms of keeping possession and grass covered." The midfield area is a cause for concern for Southgate and he is looking to add one or two faces capable of playing both in the middle and on the right side.

However, despite being linked with players like Brown, Southgate remains confident Cattermole will eventually develop into the long-term replacement for Boateng.

"George's position in the middle will be Lee's strongest position," said the Middlesbrough boss. "Lee had to play in a position that he had never played before and he did that well.

"But I have learnt young players can have great futures but it's naive to think they can go on and achieve things with six or seven of them in the same side at the same time. They need to be surrounded by experience."

Southgate remains restricted in his transfer dealings until he knows where Middlesbrough stand in their attempts to secure Mark Viduka on a long-term deal.

West Brom's failure to overcome Derby in the Championship play-off final on Monday means Baggies striker Diomansy Kamara remains a top target whose chances of signing have increased.

Kamara, however, will have an offer from Serie A side AS Roma to mull over and Southgate may not be in a position to seriously bargain until Viduka has confirmed if he is staying or going.