Hughie Fury criticises Joseph Parker for meeting Eddie Hearn
Hughie Fury has called promoter Eddie Hearn a "cockroach" and said he will unify boxing's heavyweight division with cousin Tyson Fury.
The 22-year-old fights Joseph Parker for the WBO title on 23 September.
He feels Parker's team are "looking past" him, having held meetings with Hearn, who promotes fellow Briton and WBA and IBF champion Anthony Joshua.
"I would take me completely seriously because I am coming for that belt," said Fury.
"Eddie Hearn, a cockroach, that's what you are, with your big stiff fighter, I'm coming for you next.
"When I get that belt, me and Tyson are unifying this full division together. Full stop."
Tyson Fury could compete on the undercard of the bout if boxing authorities reinstate his licence, according to Peter Fury, who trains the cousins.
He has not fought since overcoming Wladimir Klitshcko in 2015 to take the WBA, IBF and WBO world heavyweight titles.
Tyson Fury vacated his titles in October 2016 to concentrate on his "medical treatment and recovery" after admitting taking cocaine to deal with depression.
The self-proclaimed 'Gypsy King' refused to be drawn on his own future at Tuesday's news conference in Manchester.
Peter Fury - father of Hughie - believes the meeting with Parker at the Manchester Arena is a "50-50 fight".
He added: "It's a massive opportunity for Hughie. A big step up to world level. Parker is no mug, a serious contender."
Both Parker and his trainer Kevin Barry stated they respected Hughie Fury and said meetings with Hearn were lined up purely because they were in the UK.
Parker, who has defended the WBO title once since winning it in 2016, has only competed outside his native New Zealand in four of his 23 fights.
"I'm not taking him lightly or looking past him," said Parker, 25. "Since becoming champion it's just motivated me to train even harder."
Hughie Fury and Parker were due to meet in Auckland on 6 May but the Briton withdrew with a back injury.
He boasts a record of 20 wins from as many fights, while Parker has won all of his 23 contests.