The two factions of the Sri Lanka Freedom Party (SLFP) have held talks to try and unite to face local council elections, now likely to be held in mid-February.
"The efforts failed because they (the Sirisena faction) did not want to leave the government. We cannot agree to any alliance with the UNP," Rajapaksa said yesterday, addressing a political rally of his new party - Sri Lanka Podujana Peramuna (SLPP) - in the central hill town of Badulla.
Rajapaksa has been reluctant to publicly associate with SLPP until yesterday.
Rajapaksa backers in the SLPP want the Sirisena-led SLFP to leave the current unity government with Prime Minister Ranil Wickremesinghe's United Natinal Party (UNP).
The UNP and SLFP formed the unity government in 2015 after Rajapaksa lost to Sirisena in the presidential election.
Rajapaksa, who had sacked Sirisena from the party after he emerged as the common opposition challenger, had passed on the SLFP leadership to the incumbent president following his stunning victory.
Disclaimer: No Business Standard Journalist was involved in creation of this content