CNN today began its legal challenge to be allowed to film the Shipman inquiry when it reopens next week.

The inquiry, headed by high court judge Dame Janet Smith, heard that CNN had a "presumptive right" to broadcast the investigation into the deaths of 466 patients of former GP Harold Shipman, who is serving life for the murder of 15 female patients.

Dame Janet opened a day-long hearing in Manchester by telling the inquiry she was allowing today's proceedings to be filmed as part of a pilot.

She said today's application by CNN was "a fresh matter altogether" from an earlier application by the BBC, which was turned down.

But she added: "It is surprising to me that, if this inquiry was so important to CNN, it didn't make this application some months ago."

Geoffrey Robertson QC, who is representing CNN, said live broadcasting of the inquiry would assist the process of a thorough investigation and would impart more information than reports in the press.

"It is our impression that while press reporting has been reasonable in Manchester and the local press, it has not been to any extent covered in the national press," Mr Robertson said.

"Broadcasting by CNN has a real prospect of assisting the inquiry through the fact it encourages interest from other countries and other experts."

Mr Robertson said witnesses who objected to being filmed could be have their identities hidden by "pixilising" their image on screen.

He added the inquiry also had the power to ban the cameras from filming a particular witness if they objected.

Ann Alexander, a solicitor representing Thameside Families Support Group, said in a statement that the families were opposed to the broadcasting of phase one of the hearing.

The inquiry heard that 23 former patients of Dr Shipman's surgery, who are due to give oral evidence, were asked for their views on the filming of the proceedings.

Of those, only eight were in favour of broadcasting all phases of the inquiry.