After being snubbed by AIADMK, actor-politician Vijaykant's DMDK and CPI(M) on Monday announced a seat-sharing agreement for the civic polls in October.
CPI(M) state unit secretary G Ramakrishnan said the present situation was borne out of AIADMK's disregard for "ethics of negotiations" with party chief Jayalalithaa "unilaterally" announcing candidates while talks were on.
"We had aided AIADMK in coming to power after the April 13 polls (by being part of the alliance) and have been working as a constructive opposition since then," he told reporters here at the end of the party's state committee meeting to take a call on a tie-up with DMDK.
While CPI(M) had wanted to extend the ties with AIADMK for the civic polls, AIADMK high command had unilaterally announced candidates, he said.
On the agreement with DMDK, he said further talks would be held to finalise the seats and there would be "some give and take" as some candidates on either side who had filed nominations would have to withdraw from the polls.
Asked whether the party was a part of AIADMK-led alliance, he said his party had only entered into a seat-sharing agreement with the former for the Assembly polls.
Efforts would be taken to bring like-minded parties in this front which was formed as a non-Congress, non-DMK, non-AIADMK and non-BJP front, he said.
After having fought the April 13 polls as allies, AIADMK failed to allocate seats for allies, DMDK and Left parties, prompting Vijayakant to announce going it alone.