The chair of the Northcote National Party, Camryn Brown, noted that if Halbert had been waiting for a test since Saturday, then he too had fallen foul of the rules, with numerous social media posts showing him out and about in the intervening days, including at a crowded RSA meeting.
Halbert issued a clarification saying he had not been tested because he was symptomatic, but simply as part of a testing programme used by Auckland MPs coming to Wellington.
But this scheme ended in January.
Halbert said he continued using the testing scheme after it expired as "a precaution".
"As a precaution I carried on getting this routine testing given that I come into contact with vulnerable constituents. I am not and have not been symptomatic over that time. I apologise for not following the updated Ministry of Health guidance around asymptomatic testing." he tweeted.