John Banks says the battle to clear his name is far from over.

The former Auckland mayor and Act MP was today convicted of filing a false electoral return.

Outside the High Court at Auckland this morning, after Justice Edwin Wylie sentenced the 68-year-old to two months' community detention and 100 community work, Banks said he would appeal, citing "compelling new evidence".

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Banks said he respected the court and the judge's finding before dropping the bombshell that there was further information not presented during trial.

"Since the finding of guilt, fresh, new, unimpeachable, water-tight evidence has emerged. That new evidence completely contradicts much of the evidence given in the court," he said.

"We're looking forward to taking that ... to the Court of Appeal and in the process of time, that will completely exonerate me of these charges."

During the judge-alone trial in June, the Crown argued Banks' failed mayoral campaign received two $25,000 donations from Megastuff Ltd on Kim Dotcom's behalf in June 2010 and $15,000 from SkyCity in May that year.

While Justice Wylie ruled the charge in relation to the SkyCity donation was not proven, he believed Mr Dotcom was telling the truth.

Yesterday's sentencing began as surprisingly as it ended; with Banks' lawyer David Jones QC accepting a conviction on behalf of his client when it was previously indicated he would seek a discharge.

The offence carries a maximum penalty of two years in prison or a fine of up to $10,000 but the judge said the offending was not at the upper end of the scale.

"You failed to disclose only two donations. There is nothing to suggest it was a pattern of offending," Justice Wylie said.

But it was not a victimless crime, he said, the victim of the offending was the community at large.

Watch: John Banks found guilty

Act MP John Banks will remain in Parliament until it rises at the end of July despite being found guilty of filing a false election return today, Parliament's Speaker David Carter has confirmed. Mr Banks was today found guilty of knowingly filing a false electoral return during his 2010 Auckland mayoralty bid, an offence severe enough to see him automatically ejected from Parliament.

Mr Jones said the guilty verdict alone had a huge impact on his client and Banks maintained his innocence, and a pre-sentence report noted Banks called the judge's verdict "bewildering".

Banks' wife had since moved to Central Otago because of the public scrutiny but continued to support him, the court heard.

During an interview with a probation officer Banks called the fiasco a "process of incremental humiliation".

After the hearing, Wellington accountant Graham McCready who brought the charges against Banks announced: "The universe is unfolding as it should."

Unlike last time he refused to sing outside court, telling reporters he would celebrate by doing his laundry and having lunch with a friend.

He will pursue Banks for $45,000 in costs, which he said would go to charity if he was successful.

Banks' sentence of community detention - essentially a curfew for four days a week - was due to begin on Thursday but will be put on hold because of the impending appeal.

Watch: Gerry Brownlee on Banks' conviction

Leader of the house Gerry Brownlee comments on ACT MP John Banks' conviction where he was found guilty of filing a false electoral return.