American artistic swimmer Anita Alvarez had to be rescued from the pool by her coach at the World Aquatics Championships after losing consciousness following her solo free final routine in Budapest.

Andrea Fuentes, a four-time Olympic medallist in synchronised swimming for Spain, sprung in to action after she saw Alvarez sink to the bottom of the pool.

The 25-year-old received medical attention before being taken away on a stretcher.

It was the second time Fuentes has had to rescue Alvarez after she leapt into the pool during an Olympic qualification event last year and pulled her to safety along with the American's swim partner Lindi Schroeder.

"It was a big scare," Fuentes was reported as saying by Spanish newspaper Marca.

"I was scared because I saw she was not breathing, but now she is doing very well.

"She only had water in her lungs, once she started breathing again everything was OK."

And speaking to Spanish radio, she said: "It felt like a whole hour. I said things weren't right, I was shouting at the lifeguards to get into the water, but they didn't catch what I said or they didn’t understand.

"She wasn’t breathing. I went as quickly as I could, as if it were an Olympic final."

Alvarez finished seventh in the final, with Yukiko Inui of Japan winning gold. Ukraine's Marta Fiedinaand Greece's Evangelia Platanioti filled the minor podium places.

In a statement on the US artistic swimming Instagram page, Fuentes said Alvarez would be assessed by doctors before a decision was made on her competing in Friday's team event.

Fuentes said: "Anita is OK – the doctors checked all vitals and everything is normal: heart rate, oxygen, sugar levels, blood pressure, etc... all is OK.

"We sometimes forget that this happens in other high-endurance sports.

"Marathon, cycling, cross country... we all have seen images where some athletes don’t make it to the finish line and others help them to get there.

"Our sport is no different than others, just in a pool, we push through limits and sometimes we find them.

"Anita feels good now and the doctors also say she is OK.

"Tomorrow she will rest all day and will decide with the doctor if she can swim free team finals or not. Thank you for all of your well wishes for Anita."