The five-team tournament will be played from August 28 to September 20.
According to Sri Lankan newspaper Daily News, Pathan and Guptill are among 143 overseas cricketers in the list for the tournament that will begin on August 28 and run until September 20.
"There are about 143 overseas players in the list who are very keen to play in this tournament and now it is up to the respective franchises to select these cricketers," a high ranking official at Sri Lanka Cricket (SLC) told Daily News.
"We have also asked the local clubs to nominate two players for this event and so there would be a total of 48 top domestic players from the 24 Premier Clubs who would be eligible to represent the four franchises.
"In addition, we have a total 80 national players who are currently contracted with SLC and they will also be strong contenders to make it to the final squad.
"Some of the Premier Clubs have also named young promising players in the Under-23 and Under-19 category but altogether it is up to the four franchises to make a final decision in picking their squad."
The 23 match league will be played in four international venues – R. Premadasa Stadium, Dambulla Stadium, Pallekele Stadium and Mahinda Rajapaksa Stadium in Hambantota.
Five teams named after the cities of Colombo, Kandy, Galle, Dambulla and Jaffna will participate in the League.