TV reports said that the stern action has been taken following intense sibling rivalry between Azhagiri and Stalin.
Sources said that Azhagiri has been suspended after meeting party president Karunanidhi this morning. The decision was also taken by Stalin along with Karunanidhi.
The suspension comes ahead of the DMK's state conference in Tiruchirapalli next month.
DMK general secretary K. Anbazhagan said Alagiri was creating confusion in the party ranks and criticising the disciplinary action taken against some colleagues for "anti-party activities".
He said the continuation of Alagiri in the party was not proper and would destroy discipline. So, he said, Alagiri had been "temporarily suspended".
"The members should accept this decision taken in the interests of the party and should stand united," Anbazhagan said.
Karunanidhi had last week warned Azhagiri and others that the party would take action, including removal from primary membership, against those who voiced views contrary to the official line.
Alagiri was suspended after meeting party president Karunanidhi this morning.
The family rift is out in open just few months before the nation goes to the Lok Sabha elections 2014.
Following the warning by his father and DMK President, Azhagiri even met him at his residence in Chennai last week.
The DMK had recently disbanded its Madurai unit as some functionaries violated the party discipline.
DMK is keen on roping in DMDK into its fold to fight the general elections while the latter has not expressed any views on the issue.