An ageing nun who stole over $800,000 to bankroll a gambling habit and fund lavish holidays was jailed for a year in California on Monday.

Mary Margaret Kreuper, 80, swore to a life of poverty when she took her vows six decades ago.

But as principal of a Roman Catholic elementary school near Los Angeles, she diverted $835,000 of school funds to pay for gambling jaunts in Las Vegas, a court heard.

She also used the money to take luxury trips to swanky resorts like Lake Tahoe, where well-heeled tourists gather to cruise in the summer and ski in the winter.

"I have sinned, I have broken the law, and I have no excuses," Kreuper told the court, according to The Los Angeles Times.

She said her crimes were "a violation of my vows, the commandments, the law, and above all the sacred trust that so many had placed in me."

Kreuper admitted wire fraud and money laundering during a hearing last year.

The court was told how money sent to the school to pay for tuition and charitable donations was instead funnelled into secret accounts that Kreuper controlled.

When an audit threatened to expose the scheme, Kreuper told employees to destroy incriminating documents, the court heard.

The Times reported that when she was initially confronted by the Archdiocese of Los Angeles, Kreuper argued that priests were better paid than nuns and that she thought she deserved a raise.

Kreuper's lawyer, Mark Byrne, asked that she be allowed to serve her time at the convent where she had been kept since her crimes were uncovered in 2018.

He said she was addicted to gambling. "This is not an excuse for what she did," he said, according to the Times, "this is merely an explanation."

District Judge Otis D. Wright II told Kreuper that he had wrestled with what to do with her, and acknowledged she had been a good teacher for many decades,

"But somewhere along the line, you just ran completely off the road, and I think you understand that. At least I hope you do," he said.

Kreuper was sentenced to 12 months and one day behind bars.