Karunanidhi's response came in an interview to one of the leading Tamil dailies 'Dinamalar,' in which the 90 year-old DMK patriarch also refrained from commenting on a possible tie-up with the saffron party post-elections.
"The hectic election campaign by Modi shows he is a hardworker. He is also a good friend of mine," he said when asked about his 'personal opinion' on the Gujarat Chief Minister.
Asked if his announcement in the recent DMK state conference that his party would not align with 'communal forces', meant BJP, Karunanidhi shot back "are you giving a confessional statement that BJP is communal."
When asked if there was a chance for DMK joining BJP-led alliance after elections, he said he "cannot speculate and tell what will be the situation after the Lok Sabha polls."
The DMK chief's response assumes significance as it comes two months after he ruled out any alliance with the BJP besides former ally Congress, in his party's general council.
However, DMK Organising Secretary T K S Elangovan sought to play down Karunanidhi's remarks saying it was his personal opinion.
"It shows his political maturity. It is however his personal opinion. Our leader [Karunanidhi] has regards for Sonia (Gandhi) and vice versa," he said indicating that there is no political significance in such observation.
Modi has attacked the DMK in the context of the 2G spectrum scam in which senior party leaders Kanimozhi, Karunanidhi's daughter, and former Telecom Minister A Raja are accused.
Incidentally, Karunanidhi had in December denied media reports about possible alliance between DMK and BJP. DMK was part of the Vajpayee-led NDA before it pulled out ahead of the 2004 elections.
DMK was keen on roping in actor-politician Vijaykant's DMDK in the alliance-led by it for the Lok Sabha polls. But DMDK, which is also being wooed by BJP, is yet to announce its decision.