Fiorentina sporting director Daniele Prade has revealed that the club are yet to reach an agreement for Bayern Munich striker Mario Gomez.
Gomez has emerged as Fiorentina's top summer transfer target with the Germany striker expected to leave the Treble winners.
However, Prade insists the Serie A side will not break the bank to try and bring Gomez to the Artemio Franchi.
"Gomez is a player that interests us, but in this moment there aren't any agreements to close the negotiation," Prade told reporters.
"He will cost a lot and we must adhere to the economic parameters we have set ourselves.
"Our relationship with Bayern Munich is solid though.
"The player is interested, it's just the deal is not finalised."
Prade also revealed the club are relaxed over the future of Stefan Jovetic, who has been linked with the likes of Chelsea, Arsenal and Juventus, saying they have yet to receive an offer to meet their valuation of the playmaker.
"We are very serene regarding Jovetic's future," added Prade. "The market has only just opened, and at this time, no offers have arrived [that are satisfactory]."
Hall, who made 82 appearances for the U's between 2010 and 2012, spent last season with Shrewsbury and joins United on a six-month loan.
Former Rotherham and Cambridge left-back Newey joins on a one-year deal after leaving Scunthorpe.
"They are both very experienced solid players and they add a bit of depth," manager Chris Wilder told the club's official website.
"Tom adds balance on the left side of defence and is a very good organiser as well as a good player. Asa showed us towards the end of his first spell here what a good player he can be at this level."
Oxford have already signed David Hunt, Jon Meades, Danny Rose, Josh Shama and Dave Kitson ahead of their first pre-season game at Ardley on Saturday.
