However, the Premier League champions face a battle from Serie A giants Juventus and Inter Milan to secure his services.
Sources in Italy claim all three clubs are tracking the youngster, who has established himself in the Slavia Sofia first team at the tender age of 16.
The centre back has already made 19 first team appearances in all competitions this term, and is now a regular for the Bulgarian Under-21 side.
United are preparing an offer of around £1.25million, which they hope will be enough to secure the services of one of the most exciting prospects to have come out of Bulgaria in years.
The Premier League champions will hope Velkov will be swayed by the fact that Dimitar Berbatov – one of the most famous Bulgarian footballers of all time – who spent four years at Old Trafford, and enjoyed tremendous success, winning the Premier League on two occasions.
Slavia have become aware of the mounting interest in their young defender, but will reject any offers that come their way in January.
The club are determined to keep hold of him until at least the summer, meaning United will continue to monitor his progress until the end of the season.