Tamil Nadu Chief Minister J Jayalalithaa will boycott prime minister-elect Narendra Modi's swearing-in ceremony tomorrow, sources have told India's NDTV.
Sources say the decision has been taken in the wake of Mr Modi's invite to Sri Lankan president Mahinda Rajapaksa to attend his swearing-in. Mr Rajapaksa has confirmed that he will attend.
Ms Jayalalithaa, who is said to share a good rapport with Mr Modi, will also not send any representative from her party, the AIADMK, said sources.
On Friday, the Tamil Nadu chief minister had described as "unfortunate" the invite to Mr Rajapaksa.
The invite to the Lankan president has "deeply upset the people of Tamil Nadu and wounded their sentiments," Ms Jayalalithaa had said in a statement, which added "Particularly, with regard to the relationship of the new Central Government with the Government of Tamil Nadu, it would have been better if this ill-advised move had been avoided."
While campaigning for the general elections, Mr Modi and Ms Jayalalithaa had attacked each other politically, but after each posted a spectacular win - Mr Modi nationally and Ms Jayalalithaa in her state - they exchanged warm greetings, congratulating each other.
In the past both have attended the other's oath ceremonies as chief ministers.
Most political parties in Tamil Nadu allege that civilian casualties and human rights violations against Tamils peaked during the last leg of the war against the LTTE with Mr Rajapaksa in charge. The BJP's own ally, the MDMK, said Mr Rajapaksa's presence in the oath ceremony will hurt the feelings of the Tamil people. The DMK, headed by M Karunanidhi, said Mr Modi could have "avoided" inviting the Sri Lankan President and also that the Prime Minister should "understand the feelings" of the people of Tamil Nadu.
It is a very sensitive political issue in Tamil Nadu, where assembly elections are due in 2016.