Aidas Gedvilas, the group's leader, says they decided to expel Dmitrijev on Wednesday.
"When the information published on social media reached us, the group (...) decided unanimously and categorically that we are strictly distancing ourselves from such views of Sergej Dmitrijev and that further joint work is impossible," he told BNS on Thursday.
The move follows a news report by the Delfi news website that Dmitrijev had posted a comment under a Facebook post marking two years since Zakharchenko's death, reading "Glory to the memory of the hero!"
Zakharchenko was one of the separatist leaders of eastern Ukraine and a political and military figure of the non-recognized Donetsk People's Republic.
"The Labor Party has always stood for peace, democracy, human rights. Therefore, we had to deal with this issue when we learned about it," Gedvilas told BNS.
The Labor Party will ask Dmitrijev, who was elected to the municipal council on the party's ticket, to resign as a councilor, he said.
Dmitrijev, the chairman of the Lithuanian Russian Union, is also on the Labor Party's list of candidates for next month's parliamentary election, at number seventy-three.
"We don't want him to run, but there's no tool to remove him from the list under the current rules," Gedvilas said.
The Labor Party's group in the municipal council has four members after expelling Dmitrijev.
The Labor Party's leader Viktor Uspaskich told BNS the party's council had made a decision to distance itself from Dmitrijev's statements and told the election headquarters to turn to the Central Electoral Commission and asked for this candidate to be removed from its list. In his words, it was done soon after media reports about their candidate's position.
But under the CEC schedule, parties or candidate could withdraw their election document by September 6, i.e., before the publication on Dmitrijev.
Following Dmitrijev's expulsion, the Labor Party's group now has four representatives on Vilnius City Council.