Labor party operatives have been accused of stealing sensitive voter details from the Victorian Greens, after one of them bragged about going "undercover" during a door-knocking campaign.

Two Labor members volunteered at a recent Greens doorknocking event in Melbourne's inner north, against the Adani coal mine in Queensland.

In the process the pair, Jesse Cuthbert and Ivan Xie, were given electoral data collated by the Greens.

It is understood that Mr Xie has volunteered and briefly worked for federal Wills MP Peter Khalil, but has not been employed for some time.

Political parties are given access to electoral data which they can collate and use for targeted campaigning.

The duo initially did not return the data given to them at the doorknocking event, which prompted an angry letter from the Greens state director Clare Quinn to her ALP counterpart.

"I am writing to let you know that on 8 July 2017, two of your members, attended Greens community door-knocking events and stole electoral data in hardcopy," Ms Quinn wrote.

Labor operative Jesse Cuthbert comments that he was "undercover" while door-knocking with the Greens. ( Facebook )

On Facebook, Mr Cuthbert boasted that he was "undercover" when Labor members saw a picture of him with Greens MP Adam Bandt.

"I was on [a] mission," he posted.

It is not the first time Labor has been accused of grubby political tactics. In March, members close to Opposition Leader Bill Shorten faced court after vandalising Greens political material on election night.

The court fined them $1,000 each and said they acted "more like schoolboys" than men.

The ALP is also being investigated by the Ombudsman for alleged misuse of electorate staff in the 2014 state election.

The Australian Electoral Commission (AEC) said the alleged behaviour did not appear to breach the Commonwealth Electoral Act.

"The AEC has recommended that, if the party continues to hold concerns about the incident, they should take immediate action to refer the matter to the police," a spokeswoman for the commission said.

ALP 'incredibly disappointed' with pair

As soon as Labor party acting state secretary Kosmos Samaras was informed of the alleged theft, he demanded the pair return the data, which has since happened.

Mr Samaras said the party was "incredibly disappointed in their actions, which were reckless".

In a letter to Ms Quinn, he said the Victorian branch did not condone the actions.

"Let me assure you that we take such matters seriously and will investigate the matters you raise fully and in a timely fashion," he said.

The ABC understands the pair also face internal party discipline.

The theft occurred in the federal seat of Wills, which includes Brunswick and Coburg.

The seat, once a Labor stronghold and home to former prime minister Bob Hawke, is becoming increasingly marginal, with the Greens scoring a 10 per cent swing at last year's federal poll.

Mr Xie did not wish to comment when contacted, and Mr Cuthbert did not return calls.

Ms Quinn said that the data theft, so far out from an election, showed Labor's desperation.

"When Labor gets desperate they get dirty. Labor needs to take action on its toxic campaigning culture," Ms Quinn said.

"The Greens are committed to positive, fair campaigning and don't need to resort to dirty tricks."