Top Australian scientists will spend the next three weeks studying causes of the mass fish kill in NSW after accepting a request from federal Labor leader Bill Shorten.

Up to a million fish died in the Darling River at Menindee last week when a cool change swept through the region, killing off an existing algal bloom and depleting oxygen which worsened water quality.

Mr Shorten on Friday wrote to Professor John Shine, a biochemist, molecular biologist and president of the Australian Academy of Science.

In the two-page letter, seen by AAP on Sunday night, Mr Shorten states that “rightly troubled” Australians “deserve a speedy yet thorough examination of why this has taken place, based on the best possible science”.

“My immediate priority is to uncover what has taken place, and ensure we have the scientific evidence before the parliament to inform decisions for a healthy river system,” Mr Shorten wrote.

The opposition leader has asked for advice on four points including how and what caused an event of such magnitude, if chemicals and fertiliser played a part, and whether current Murray-Darling water diversions or management practices have sparked or exacerbated “the scale of this disaster” in the important river system.

In addition, Mr Shorten is seeking advice on any possible “step change” to water inflows due to climate change.

He also states that Labor environment spokesman, Tony Burke, is able to convene a meeting of Australian multidisciplinary experts as soon as possible if the academy can advise them on appropriate people to include.

Mr Shorten has requested such a group provide a written report to him by February 10, ahead of federal parliament’s first sitting week.

“If we are to be responsible custodians of our country, we must restore the rivers to health, and we cannot do this without drawing on scientific experts,” he wrote.

A spokesman for Mr Shorten confirmed with AAP on Sunday night that the independent academy has accepted the request, which comes with a commitment from Labor that the written scientific advice be made public.

Federal Agriculture Minister David Littleproud last week said he had asked the Murray-Darling Basin Authority to convene an emergency meeting of state and federal water managers and environmental water holders.

The NSW government insists the devastating drought gripping the state is a key factor to the fish kill.

-AAP