A legal fight over runaway rugby league star Sonny Bill Williams turned into a farce at a boxing event in Newcastle, The Daily Telegraph newspaper reports.

The private investigator who tried to serve controversial adviser Khoder Nasser his court papers required police protection at the Anthony Mundine fight at the Newcastle Entertainment Centre, the Sydney newspaper says.

The newspaper published a photo on Thursday of the investigator but covered his face at the man's request for his own safety.

The investigator who needed protection from two police officers at the fight, told The Daily Telegraph: "I was only trying to do my job, but at the end of the day it was just too dangerous.

"I had one fellow following me everywhere and there were all these threats being made ...

"That's when I had to call the police to escort me out of there."

The investigator was surrounded by several supporters of Nasser when he tried to enter the VIP area just before Mundine's fight, the newspaper said.

Nasser wasn't even at the fight and the newspaper says he is planning to fly to the United Kingdom on Thursday to join Williams.

Williams on Wednesday night received his visa from French Consulate officials and on Thursday will travel to France where he hopes to begin a new $3 million career with rugby union club Toulon, according to the newspaper.

The incident in Newcastle is a major blow to the NRL and the Bulldogs, given they were hoping the court papers would force Nasser to come clean about the overseas location of the former Bulldogs star, the newspaper adds.

Lawyers for the NRL will again attempt to serve the papers on Thursday, possibly at the Sydney airport before Nasser boards a plane for England, according to the report.

The Sydney Morning Herald reports on Thursday that Williams' father John was sitting ringside at Mundine's fight.

After Mundine's unanimous points win over Japan's Crazy Kim in the 10-round catchweight bout, Mundine told the crowd: "I want to send a message to Sonny Bill Williams overseas.

"You all support Sonny Bill. He's my main man. Don't you boo him because he's a great man and he has great heart."

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