The actress (right) had turned her home near Salisbury in Wiltshire into a fortress since she became aware of their activities.
Police said they had been working with the German authorities and Interpol in an effort to bring criminal charges against the two men.
Acting Inspector Charles Dibble of Salisbury City Police said: "A risk and threat assessment has been carried out and we are taking these threats very seriously.
"Miss Willcox is currently receiving literature that she shouldn't be getting, though we have had no recent contact from her."
He also said that "contingency plans" were in place but he declined to give further details.
Miss Willcox, 39, who lives in the former home of photographer Sir Cecil Beaton in the village of Wilton, had hired a private security firm to protect her.
Surveillance cameras surround the Grade 1 listed house and the seven- acre estate where she and her husband live, and where her parents have a cottage in the grounds.
She also has a panic button, connected to a central alarm unit which contacts police in an emergency.
But Miss Willcox, who has recently become a presenter on BBC1's Holiday Programme, is said to be determined her stalkers will not beat her.
She told the Mail on Sunday: "It is terrifying knowing there are lunatics out there who want to hurt me - even kill me. I can't let these people know I am scared because that is how they get their satisfaction."
The 4ft 11in ex-singer is married to the rock musician Robert Fripp, who is often away touring with his band, King Crimson.Reuse content