"They have pulled out as their letter to AIFF President Praful Patel did not bear any fruit. They are yet to get any reply," a source close to the development told IANS.
While clubs like just-crowned champions Chennai City FC, East Bengal, Churchill Brothers, Aizawl FC, Gokulam Kerala and Neroca FC remained tight-lipped on the matter, a source said Mohun Bagan might soon pull the plug on their participation. "Mohun Bagan are also likely to follow suit," the source added.
Last year's champions Minerva Punjab cited the "unfair treatment" meted out by the AIFF to all I-League clubs as the reason for their decision to pull out of the Super Cup.
Earlier, eight of the 11 I-League clubs had written to Patel requesting a meeting to "seek answers" regarding the league's future.
The letter -- bearing the names of top office-bearers of Aizawl FC, Chennai City, Churchill Brothers, Gokulam Kerala, Minerva Punjab, Mohun Bagan, Neroca and East Bengal -- said the teams also wanted to discuss the potential relegation to the second division in Indian football, with the ISL "all set to be branded the top league of the country."
They alleged "interference" of AIFF's marketing partners Football Sports Development Limited (FSDL) in the decision-making in Indian football.
The three clubs which did not join were debutants Real Kashmir, Shillong Lajong, owned by AIFF Vice President Larsing Ming Sawyan, and Indian Arrows, the AIFF's developmental team.
The qualification round of the Super Cup is set to be held on March 15 and 16 in Bhubaneswar. The main round is scheduled to start on March 29.