The posters have been placed by supporters of Mr Alagiri, ahead of his 62nd birthday tomorrow, planned as a show of strength after his father hinted recently that he had chosen Mr Stalin as his successor.
Referring to the contentious posters, the party said in a statement, " Inappropriate words have cropped up which bring bad name to the party...strict action would be taken against those responsible for such acts."
The DMK is the largest ally of the Prime Minister's ruling coalition. While Mr Alagiri was deputed to represent the DMK in the union government, his brother has been rising through the ranks of the party in its home state, and is currently Treasurer of the DMK.
When Mr Karunanidhi suggested that he would endorse Mr Stalin for president, his older son responded caustically that the DMK is not like a "mutt" -a religious sect- where successors are appointed. Mr Alagiri has in the past suggested that when his father steps down, he will contest elections for president.