The trio will be using the competition as a warm-up for this summer’s FINA World Championships in Kazan.
Double Commonwealth Games champion Proud will be part of the Great Britain team in Russia, while Olympic champion Meilutyte and Sadauska will be representing Lithuania.
The World Championships take place between July 24 and August 9, with the pool swimming events starting on August 2.
The Mare Nostrum series is seen as an important event ahead of those championships.
Proud is part of the GB squad that will compete in Canet this weekend and then move to Barcelona for the second event in the series on June 10-11.
He has spent the past week in France at a Team GB training camp in Vichy.
British Swimming’s head coach Bill Furniss said: “I’m pleased with the camp. We have seen a lot of great work by athletes and coaches in what is a fantastic venue here in Vichy.
“As a team we will now take the learning from this week, together with all the team behaviours, and apply this in a competition environment across two very high-standard events in Canet and Barcelona.
“Several of the big swimming nations will be sending many of their best swimmers and I think these events will offer the highest standard of competition we have seen at the Mare Nostrum for many years.”
Proud is entered in the 50m and 100m freestyle and 50m butterfly events. On paper he is the fastest competitor in the two 50m events and ranked eighth in the 100m.
Sadausaka will be up against Proud in the 50 and 100m freestyle events. The men’s 100m competition as a staggering 114 entries.
World, Olympic and European champion Meilutyte is entered in the women’s 50m freestyle and the 50m and 100m breaststroke races.
As the world record holder, Meilutyte is ranked the fastest in the two breaststroke events, but she will face tough competition in the 100m event from Denmark’s 200m world record holder Rikke Moller Pedersen.
Meanwhile, Plymouth-born Paralympic star Jonathan Fox has been forced to pull out of July’s IPC Swimming World Championships in Glasgow due to an on-going shoulder injury.
The world record holder and London 2012 gold medallist said: “It’s been a really tough decision to pull out of the World Championships.
“I have been working really hard but after meeting with my coaches and medical team it is going to be better in the long-term for me to focus on just my rehab.
“Competing at my third Paralympics remains my ultimate goal and I will continue working on my rehab to give me the best hope of returning to that podium.
“I’d like to thank everyone for their support and wish the team good luck in Glasgow.”
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