Australia's media regulator launched an investigation on Thursday into a prank call by a radio station to a London hospital treating Prince William's pregnant wife, after the nurse who took the call committed suicide.

Jacintha Saldanha was found hanged, police told a coroner's inquest in London, days after the 46-year-old put the hoax call through to a colleague who disclosed details of the treatment being given to William's wife Kate, who is suffering from acute morning sickness.

The stunt by DJs at Sydney radio station 2Day FM made headlines around the world as did news of the death of Saldanha, who was married with two children. Her body was found at staff lodgings near King Edward VII hospital last Friday.

Detective chief inspector James Harman told the coroner, an official who certifies the causes of deaths, that Indian-born Saldanha was found hanging by a scarf. Three notes were discovered at the scene.

"There were also some injuries to the wrist," he told the coroner Fiona Wilcox in a small, wood-panelled court packed with reporters. Saldanha's family did not attend.

In a brief statement, the Australian Communications and Media Authority said it had opened a formal inquiry to see if 2Day FM had breached its licence conditions and commercial radio codes of practice.

The codes state a radio station must not broadcast the words of an identifiable person unless the person has given permission for the broadcast. The station has said it tried to contact the hospital several times before it broadcast the prank call.

The authority can impose new licence conditions if it finds a breach. In extreme cases it can suspend or cancel a broadcasting licence.

Southern Cross Austereo, parent company of 2Day FM, has apologised for the stunt. It said on Tuesday it would donate its advertising revenue until the end of the year to a fund for Saldanha's family, with a minimum contribution of $525,000.

Southern Cross and its two presenters, Mel Greig and Michael Christian, have faced a barrage of criticism.

Greig and Christian have both been suspended and their show has been scrapped. They appeared on Australian television to say Saldanha's death had left them heartbroken.

British lawmaker Keith Vaz, who represents Saldanha's family, said he had written to Southern Cross to express his dissatisfaction.

"There has been no written apology, no request for a meeting with the family and no attempt to travel to the United Kingdom to express contrition," Vaz wrote in a letter to Southern Cross chief executive Rhys Holleran that he released to the media.

The hospital has said Saldanha had not been criticised or disciplined for taking the call, although Vaz said he wanted an inquiry to establish the facts.

Harman said British police were looking at emails that he said would help establish what led to Saldanha's death. They would speak to a number of witnesses and New South Wales police in Australia.

Wilcox formally opened and adjourned the inquest, setting a date of March 26 for a full hearing. – Reuters