Singapore will host the World Aquatics Championships in 2025 after the Russian city of Kazan was stripped of the event over Moscow's invasion of Ukraine.

It will be the first time that the events will be held in a Southeast Asian city. More than 2,500 athletes are expected to participate.

"With a back-to-back-to-back trio of World Aquatics Championships in Asia – following Fukuoka this year and Doha in 2024 – the continent is demonstrating exceptional commitment and ability when it comes to welcoming the world's best aquatic athletes," FINA President Husain Al-Musallam said.

The Championship includes aquatic sports of swimming, water polo, diving, artistic swimming, open water swimming and high diving.

FINA did not announce the specific dates for the championships

Meanwhile IOC president Thomas Bach has called on Ukraine to drop threats of a boycott of the 2024 Olympics over the participation of Russian and Belarusian athletes.

Ukraine hopes to secure widespread international support for a ban on Russian and Belarusian athletes after the IOC opened the door for them to compete as neutrals in Paris.

Ukrainian President Volodymyr Zelenskiy has urged the IOC to ban Russia from the Olympics, and Olympic bodies and lawmakers in the Nordic and Baltic regions have backed Ukraine.

In a letter to Ukraine's National Olympic Committee (NOC)president Vadym Huttsait, seen by Reuters, Bach said claims that allowing Russian and Belarusian athletes back into the Games would promote the invasion were "defamatory".

The IOC has said a boycott will violate the Olympic Charter and that its inclusion of Russian and Belarusians is based on a UN resolution against discrimination within the Olympic movement.

"The participation of neutral athletes with a Russian or Belarusian passport at the Olympic Games Paris 2024 has not even been discussed in concrete terms yet," Bach said.

"Therefore, your letter... to your fellow NOCs, to the International Federations, IOC Members and to future Olympic hosts, pressuring them in an attempt to publicly influence their decision making, has been perceived by the vast majority of them as, at the very least, extremely regrettable.

"It is the responsibility of every NOC... to uphold the fundamental principles of the Olympic Charter."

The IOC announced last month that athletes from the two countries might be allowed to earn slots for the Olympics through Asian qualifying and compete as neutrals, with no flags or anthems.

Paris mayor Anne Hidalgo has said it is inconceivable to have Russian athletes marching as a delegation while "bombs are still raining down on Ukraine".

"There are no plans for a Russian or Belarusian delegation or the flags of these countries at the Olympic Games Paris 2024," the IOC said in a separate statement on Thursday.

"The only option that could be considered are individual, neutral athletes."

Paris 2024 organisers have said they will abide by the IOC's decision on the issue.