Bernard Tomic has called Lleyton Hewitt a "liar" and denied threatening the Australia Davis Cup captain's family.

An ugly war of words within Australian men's tennis has overshadowed the home country's achievements on court and shows no sign of dying down yet.

It began on Monday when, after a first-round loss, Tomic accused Hewitt of favouring some players over others and said no-one wanted him as Davis Cup captain.

Hewitt then responded in an incendiary press conference on Thursday, calling Tomic a clown and claiming the 26-year-old had tried to blackmail him and threatened him and his family.

"The threats I've received for me and my family, that I've had for a year and half now, I don't think anyone would reach out to a person who speaks like that," said Hewitt.

Now Tomic has fired back, telling the Herald Sun: "I have never threatened his family. Nice, Lleyton. To think how low of a person you actually (are), and why the Australian public never liked you.

"I got nothing to do with your family and I don't care what's wrong with you, you liar."