The 23-year-old centre-back signed a loan deal with Peterborough last summer while he was recovering from a knee injury.
After returning from injury in October, Watts played eleven times for the League One side, starting seven of them.
The loan was extended earlier this month, but Watts picked up a hamstring injury during a training season which could result in his season being over.
Peterborough wanted to send Watts back to Newcastle to sign a replacement centre-back in the ongoing transfer window, and MacAnthony attempted to convince the Magpies to take the youngster back three times while getting rejected on each occasion.
“Correct”, MacAnthony wrote on Twitter, when asked if he tried to send Watts back.
“Asked 3 times and turned down 3 times.
“Life of an EFL club at times.”
It remains to be seen whether Peterborough will be able to convince Newcastle in the dying hours of transfer deadline day to take Watts back to St. James’ Park so that the Posh can sign a replacement player.