The Magpies are eager to find bargains in the January window, as there is still uncertainty regarding a potential takeover at the north east outfit.
Rafa Benitez's side are believed to be interested in the 22-year-old Hendry but Crystal Palace and Southampton have also been linked.
Newcastle could also face competition from north of the border, with Celtic boss Brendan Rodgers saying he was impressed with the youngster on their meeting with Dundee in October.
He said: "The boy Hendry at the back I thought was excellent," said Rodgers. "He’s quick and strong and is a good size.
"Scotland need centre-halves and that looks like a good kid. He’s tall, he can run and he can pass. He looks a talent."