RIO DE JANEIRO (REUTERS) - Olympic organisers cancelled diving training on Friday morning (Aug 12) and shut the pool in an attempt to restore the water to its original blue colour.

The pool turned an emerald green earlier this week, becoming the subject of numerous jokes and creating a headache for the organisers.

An adjacent pool, being used for water polo and synchronised swimming, has also started to change colour.

"We confirm that diving training in Maria Lenk Aquatics Centre's pool is cancelled this morning," Rio 2016 said in a statement.

"The reason is that the water must be still so the pool can return to its blue colour as soon as possible. Athletes are performing dry training this morning in Maria Lenk," it said, referring to a section of the venue where divers can practise using trampolines, platforms and harnesses.

The organisers said the pool would reopen later on Friday for training as well as for the women's individual 3m springboard preliminaries.

World swimming governing body Fina said the colour change was the result of a failure by the organisers to sufficiently treat the water after tanks at the venue ran out of pool chemicals.

The organisers responded by putting more chlorine - a chemical that kills algae and helps to keep water blue - in the pool and its neighbour but water polo players later complained about stinging eyes.