Liverpool on Thursday completed the signing of Argentinian defender Emiliano Insua on an 18-month loan deal.

The teenage left back, who has represented his country at U-20 level, was signed from Boca Juniors and hailed by Reds boss Rafael Benitez as "a good, young player with a lot of potential."

Sheffield United moved to bolster their forward line with an unexpected swoop for striker Jon Stead, who joins from Sunderland in a deal worth up to 1.25 million pounds.

Stead, 23, has been on loan at Derby for the last three months and Sunderland boss Roy Keane decided to sell him after spending two million pounds on the recruitment of Arsenal teenager Anthony Stokes.

Stead was a 1.8-million-pound signing for Sunderland when they bought him from Blackburn in 2005, but he managed just one goal as they were relegated from the Premiership.

Sheffield United manager Neil Warnock, who had failed with a bid for highly-rated Preston striker David Nugent, insisted he had got a bargain.

"I know there will be critics, but value for money, his age, it's a great signing for me," he said. "Jon had a poor goalscoring spell with Sunderland, but he had a fantastic time at Blackburn when he kept them up almost single-handed.

"In terms of work ethic, he is excellent. The fans will see someone who will give blood for the club, and I think they'll take to him.

"With something to prove, he can become the best value-for-money striker in the transfer window."

Stead said he was optimistic about rediscovering the form he displayed in his Blackburn days.

"There aren't many positives to come out of the last 18 months, but now is the time to put that to bed and look forward to what I hope will be a good career here, and hopefully I'll bring goals.

"After my loan spell at Derby and getting some games under my belt over the past few months, this move has come at the perfect time for me."

Manchester City full-back Ben Thatcher meanwhile joined Charlton after the two clubs agreed a 500,000 pound fee for the former Wales international.

"The finance we can gain from Ben going can be invested in other positions in the team," said City boss Stuart Pearce. "I believe I have enough cover to cope in his absence."

Pearce looks set to lose American midfielder Claudio Reyna, who has expressed a wish to return to the United States for personal reasons.

Thatcher's imminent arrival at The Valley prompted Charlton boss Alan Pardew to allow former Liverpool defender Djimi Traore to leave for Portsmouth for a fee believed to be in the region of one million pounds.

Portsmouth have also signed France Under-21 midfielder Arnold Mvuemba on loan from Rennes until the end of the season.

Championship leaders Birmingham agreed a fee of 2.5 million pounds for Luton's 14-goal striker Rowan Vine. A further 500,000 pounds will be payable if Birmingham go on to clinch promotion back to the Premiership.

Birmingham's promotion-chasing rivals Derby were also involved in transfer action on Thursday, snapping up Scotland winger Gary Teale from Wigan for 600,000 pounds.

Teale is Derby's fourth signing of this transfer window with manager Billy Davies already having recruited David Jones from Manchester United, Craig Fagan from Hull and Stephen Pearson from Celtic.