The mayor of Paris has swum in the Seine in an effort to prove its cleanliness for the Olympics outdoor swimming events - but questions remain about its quality.

After months of anticipation, Anne Hidalgo took the plunge ahead of the Games starting next week.

The mayor had originally planned to swim in the river last month but was forced to delay after tests indicated the presence of faecal matter was 10 times higher than authorised limits.

A century after swimming in the Seine was banned, French officials have been keen to prove their investment of €1.4bn to prevent sewage leaks, which has meant the waters are swimmable again.

Sporting a wetsuit and goggles, Ms Hidalgo made a splash into the river with Paris 2024 chief Tony Estanguet and senior civil servant Marc Guillaume - and sports minister Amelie Oudea Castera took the plunge earlier this week.

However, there has been no sign of President Emmanuel Macron who had previously promised to join them.

Speaking to reporters from the water, the mayor said, "the Seine is exquisite", adding it was "a little cool, but not so bad".

The triathlon and marathon swimming legs are scheduled to take place in the Seine near the Alexandre III bridge during the Olympics, which run from 26 July to 11 August, and the Paralympics, which are from 28 August to 8 September.

Why is the River Seine so dirty?

Paris has a combined sewer system, meaning both wastewater and storm water flow through the same pipes.

When there are periods of heavy rainfall, the pipes can reach capacity and this wastewater - including sewage - overflows into the River Seine instead of being sent to a treatment plant.

How has Paris tried to clean the river?

Money has been spent on building new infrastructure to catch more of the overflow water when it rains.

This has included a massive underground water storage basin next to Austerlitz train station which can hold the equivalent of 20 Olympic swimming pools and will also treat the water.

Cleaning up the Seine has been promoted as one of the key legacy achievements of Paris 2024, with Ms Hidalgo promising three public bathing areas for residents.