By Duncan Johnstone

New Zealand heavyweight boxer Joseph Parker is battling American immigration authorities for a working permit for his next fight there and may have to restrict his training buildup to New Zealand.

Parker has remained in New Zealand since beating Brian Minto in his last fight on July 6.

Parker has based most of his training in Las Vegas over the last 18 months, teaming with trainer Kevin Barry. He has been freely able to enter and exit America as a visitor because he has not been receiving a wage.

But that changes for his August 10 date in Bethlehem, Pennsylvania where he fights on the Vyacheslav Glazkov undercard against a still to be named opponent.

Parker's handlers say they are in the dark about when the matter can be sorted out. But, with the help of respected promoters Main Events, they are confident they'll get through the red tape, desperate to have the 22-year-old gain exposure to the American market via the NBC live TV broadcast there.

They had hoped to transfer to the States next week but that could change given the visa difficulties and the tight timeframe they are operating on.

"Joseph's won belts in his last three fights so we need to keep this momentum going and America is where we're heading," Barry said.

"This is the opportunity for the whole of America [to] see for the first time the fastest hands in the heavyweight division.

"If we are forced to have to have our whole training camp in New Zealand then so be it."

In a further complication, Parker has developed a cold in Auckland's poor run of weather and that could see agreement for his next engagement to be over a shorter distance than the scheduled 10-rounder.

Fellow New Zealander, light-heavyweight Robbie Berridge, fights Russian champion Vasily Lepikhin on the same promotion.