Exit International says Canberra members were interviewed by police last week over the death of Graham Daly on October 30.

The director of the group, Philip Nitschke, said the 64-year-old died from hypoxia after breathing in a low-oxygen gas.

He said members of the group were contacted and asked to answer questions at a police station.

The group arranged lawyers for those questioned.

''That in itself annoys us to find us, as an organisation, having to provide statements and the general feeling that if you inform people you will suffer police persecution,'' he said. ''As far as we can see they've done nothing illegal anyway.''

Dr Nitschke did not want to divulge Mr Daly's condition but said ''he wasn't a well person''.

A police spokeswoman confirmed they were investigating Mr Daly's death. She said a number of people had been interview by members of the Territory Investigations Group.

''Police are in the process of preparing a brief of evidence for the coroner in relation to the death,'' the spokeswoman said.

She would not confirm whether the advocacy group was being investigated.

Dr Nitschke said Exit International had records of three members of the group in Canberra ending their lives this year.

The organisation's records show the three are among 50 members throughout the country to end their lives.

Dr Nitschke said Exit International had a large number of members in Canberra.

He estimated more than 100 older Canberrans attended a seminar in June aimed at educating ''elderly people wanting to know how they can attain a peaceful death''.

The group said the ACT Investigation followed similar police inquiries in NSW and Victoria.

Dr Nitschke said a submission made by the group to a Senate inquiry on suicide argued that ''obstacles should not be put in the way of those like Mr Daly who wish to take this path''.