Manchester United have received encouragement in their bid to sign Racing Santander defender Jorge Salinas after their approach for Lewis Hall was knocked back by Newcastle United.

Standard Sport understands that Hall has been admired by Manchester United for a long time, and there is firm interest in striking a deal this summer as Michael Carrick looks to add competition for Luke Shaw at left-back.

However, according to Sky Sports, Newcastle have informed United that the 21-year-old is not available for transfer in a summer in which the club have already lost Anthony Gordon and Sandro Tonali.

In addition, with captain Bruno Guimaraes close to sealing a £75million move to Arsenal, Newcastle understandably have no intention of parting with a fourth major player this summer and are reported to have formally rejected an initial enquiry from United for Hall.

As a consequence, the Red Devils will now have to focus on alternative left-back options.

Although there have been links with Arsenal youngster Myles Lewis-Skelly, Standard Sport understands that the midfielder, who is also capable of playing at left-back, will not be targeted this summer.

Earlier this week, however, it was reported that Manchester United scouts were impressed by Salinas's displays at the Under-19 European Championships. The versatile defender still has three years remaining on his Racing contract and has also drawn interest from Barcelona.

Interest in the 19-year-old has led Racing sporting director Chema Aragon to stress that Salinas can leave, but only if the €16million (£13.7m) release clause in his contract is met.

“He has a contract with us, as you know,” Aragon said. “So, if they don’t bring the release clause, you know what’s going to happen.”

United are believed to be prepared to pay that amount for Salinas, though it had been reported that the teenager was giving priority to a move to the LaLiga champions.

Even so, Spanish outlet SPORT is now reporting that although Barcelona want the 19-year-old, they are unwilling to pay his release clause.

That could leave United as the frontrunners in the race for the left-back, with Salinas likely to be open to a switch to Old Trafford if Barcelona do not advance their interest.