ISL, who will host the two-day event from Dec. 18-19, are proposing to organise events outside the control of FINA and pay higher prize money than the governing body.
ISL said the aim of the event is to provide athletes with “the tools to build a brighter future for their sport”, starting with the creation of a global Swimmers’ Association.
Led by Ukrainian energy tycoon Konstantin Grigorishin, ISL is in a dispute with FINA after an ISL event that was set to be held in Turin this month was cancelled.
The Italian federation FIN said FINA declared the event as “non-approved” and threatened sanctions against the participating athletes.
The governing body had said in November that the Turin meeting did not meet its rules requirements.
Earlier this month, three-times Olympic gold medallist Katinka Hosszu and world champions Tom Shields and Michael Andrew also filed a lawsuit against FINA for “anti-competitive” conduct.
FINA said it would “mount a robust defence”.
The athletes attending the ISL summit at Stamford Bridge, the home of Premier League football club Chelsea, boast 15 Olympic titles between them and more than double that number of world titles.
They include 30 current swimmers and retired former champions Lenny Krayzelburg, Jason Lezak, Mark Foster and Peter Mankoc.
FINA approved on Thursday an invitation-only event — the FINA Champions Swim Series — which will make its debut next year and could be seen as a response to the challenge posed by the ISL.
The series, a three-leg competition between March and May, will offer a total of $3.9 million in prize money, making it the most lucrative swimming event in FINA history.
“In its constant effort for innovation and providing new opportunities for the stars of our sport, FINA is very pleased to launch this new competition,” FINA president Julio Maglione said in a statement.
“By creating this additional elite competition, FINA will generate a true Swimming show, where sport presentation and stars’ promotion are key concepts for a successful meet.”
Athletes will be invited on the basis of being the world champion, Olympic champion, world record holder, or the best in world ranking in each event.
These swimmers will also receive appearance fees, along with all the travel and accommodation costs.