Jerry Collins arrested in Japan

Jerry Collins in 2008. File photo / NZ Herald

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The father of former All Black Jerry Collins is desperately trying to get in touch with his troubled son.

The giant rugby star has been arrested in the central Japanese industrial city of Hamamatsu after being caught with a knife.

Local media reports said the 32-year-old muscled his way behind a shop counter in the basement level of a department store foodmarket before staff called security about 5pm yesterday.

When they arrived, Collins did not resist arrest, but produced a 17cm carving knife from his pocket and placed it on the counter. He allegedly told police he had it in his possession for "self-defence."

In Japan it is illegal to have weapons with blades longer than 15cm without police permission.

It's not clear whether he's been held in custody and further details have been scant.

His manager - Wellington-based lawyer Tim Castle - was not returning calls today to APNZ, or to Frankie Collins - the former Hurricane flanker's concerned dad.

"We're all pretty worried," Mr Collins said from his home in Porirua today.

The roadworker had been working night-shift over the weekend when he found out his son was reportedly in trouble.

Since then, he's been searching for more information.

"I've tried to get in touch with his manager, but have had no reply," Mr Collins said.

"People have been calling me and asking what's happening, but I haven't been able to get anywhere."

Collins joined Yamaha Engines Jubilo in 2011 but announced his resignation from the club to coincide with his contract ending last month.

Throughout his time in Japan, Jerry had not been in touch very often with his family.

"He never bought a phone, never left a phone number or anything," his dad said.

But that was not unusual for his son, no matter where in the world he was playing - whether for Wellington, the Hurricanes, All Blacks, Barbarians, Welsh club side Ospreys, or in Japan.

"He hardly ever called home. He'd just turn up, and when he'd go, he'd never say he'd go, he would just go.

"He doesn't like talking... he'll talk to his mates, but not anybody else. He keeps everything to himself."

He was not aware of his son experiencing any troubles off the field.

Collins' cousin Tana Umaga, who is overseas, did not wish to comment.

Collins, who played for 48 tests for the All Blacks, is being offered help by the Ministry of Foreign Affairs and Trade.