Underhanded tactics being deployed in a fierce battle over Labor preselection for seats in the ACT have continued to voting day, with a hoax text message sent to preselectors in an apparent bid to trick them into not voting.

Preselectors today begin voting on who should represent Labor at the next federal election in the ACT seats of Bean and Canberra, but a last-minute text message from an official Labor phone number has been sent, apparently trying to manipulate attendance at the vote.

"Today's preselection voting venue has been changed," the message says.

"If you can't make it, text in your vote by replying with the name of your preferred candidate, and then preferences in order to this number."

The message came from a number used by Labor in the past to contact members, however the party says it has no idea how or why the fake text was sent.

The ACT Branch of the Labor Party confirmed the text was a hoax, and that preselection would go ahead as scheduled.

"Members please disregard a text message that advertises a change of venue for today's preselection voting, it is a hoax," a post on the party's Facebook page said.

"Only votes in person or postal votes that have already been distributed are valid votes."

Candidate Kel Watt, who is running for the seat of Canberra says he has been the target of a smear campaign, in which defamatory flyers have been distributed.

Preselection will continue until next Saturday.