A High Court hearing was halted when the defendant leaped out of the dock at the start of the proceedings, stunning the court before he was subdued and taken away by security officers.

Anthony Wheble had just appeared at the Auckland High Court before Justice Graham Lang for a matter of minutes when he bounced over the waist-high dock panel as if he was going for one of the lawyers.

There were gasps from the public gallery as two security officers followed suit, pinning him to the ground after a short scuffle and pulling him out of the courtroom.

Wheble was due to be sentenced this morning for stabbing a fellow inmate's face, cutting his eyelids and slicing his throat with a homemade shank at Paremoremo - or Auckland Prison - in 2020.

He appeared wearing a dark hooded sweatshirt and a face mask on his chin, standing between two security officers before he jumped.

"It seemed to me he was trying to get to your junior but I couldn't tell," Justice Lang said, addressing Wheble's defence lawyer Baden Meyer who, like the rest of the lawyers, had their backs to the defendant standing in the dock behind them.

After a short break, Meyer told the court Wheble had smashed all the windows in the cells and was "unable to be moved or dealt with in any practical way, so [security officers] are reluctant to intervene or move him".

Anthony Wheble moments before he jumped and interrupted his sentencing hearing on Thursday. Photo / Michael Craig

Justice Lang adjourned the hearing, saying Wheble should be given the opportunity to attend his sentencing when he was calm, but could be excused if he did not want to be present.

• Auckand prisoner now convicted twice of slashing fellow inmates' throats

The judge also gave security officers leave to apply to handcuff Wheble the next time, if necessary.

Wheble had pleaded guilty in February to one charge of attempted murder for the prison attack on his fellow inmate.

The victim, Brent Charlton, had both legs in plaster when Wheble kicked him in the forehead, knocking him out before stabbing him in the face using a sharpened toothbrush with a razor blade attached to the other end.

In the one-minute attack caught on CCTV, Wheble cut both of Charlton's eyelids and slice the right side of his neck 21 times.

Wheble faces a maximum penalty of 14 years' jail for the attack, which is his third-strike offence.