Promoted Wolverhampton Wanderers have moved to strengthen the heart of their defence by signing Ronald Zubar from Marseille and taking Celtic’s Bobo Balde on trial.

The two centre-halves will fly out tomorrow to join the Molineux squad that has travelled to Australia for a two-week pre-season tour.

Zubar is Wolves’ sixth summer signing and Balde could become the seventh if the one-time Birmingham City target sufficiently impresses manager Mick McCarthy.

Having strengthened his strikeforce by spending a club record transfer fee on Kevin Doyle and bolstered his midfield with Serbian captain Nenan Milijas and England under-21 international Andrew Surman, McCarthy has more recently turned his attention towards shoring up the old gold and black backline.

Veteran goalkeeper Marcus Hahnemann arrived from Reading last month and Zubar and possibly Balde could join former Sunderland full back Greg Halford in a new-look back four.

McCarthy is delighted with the capture of Zubar who will provide central defensive competition to Jody Craddock, Christophe Berra, Neill Collins and Richard Stearman.

“Ronald is a quick, powerful defender who has played for the French under-21s and has got Champions League experience as well,” McCarthy said.

“I’m delighted we’ve managed to get him.

“We’ve had some very good reports from those watching him out in France.”

Meanwhile, experienced stopper Hahnemann has saluted the arrival of his former Reading team-mate Doyle, who became Wolves’ record signing last week.

Doyle was reunited with Hahnemann after a reported £6.5 million deal and the experienced American is full of praise for the Republic of Ireland striker.

“He came a couple of days after me which is nice,” Hahnemann said. “He missed a couple of hard days pre-season. I should have done it that way! I think they signed him to keep me happy!

“But, seriously, he’s scored tons of goals and it’s great to see him here because he’s only going to strengthen our squad because we need to score goals.

“In the Premier League that’s more important than anything and it’s fewer games, but more pressure and the games are going to be more difficult.

“So we’re going to need more players to have more choices.

“No matter who’s playing at the time we’ve got some good players here.”