The proposed children's commissioner for England could investigate the rising rate of childhood obesity, the children's minister, Margaret Hodge, said today.

Mrs Hodge said the children's champion, who is due to start work in 2005, could investigate national issues of "high interest" such as the growing number of obese children and young people, and serious cases of child abuse like the murder of Victoria Climbié.

Speaking at a New Local Government Network conference in London, the minister addressed criticism from the existing children's commissioners in Wales and Northern Ireland that the champion for child rights in England would be "one of the weakest in the world".

The Welsh commissioner, Peter Clarke criticised the remit of his English counterpart, set out in the children's bill last month, because it did not allow for investigations of individual cases of child abuse or neglect.

But Mrs Hodge said the commissioner in England should only get involved in investigating abuse if the case had "wide ramifications", in other words, if it was "another Victoria Climbié".

"What we have clearly said is what we see the commissioner doing is looking at issues which are of importance to children in the context of their world today," she told the conference.

"[Obesity] may be something else that the children's commissioner may well want to think about, talk to people about and do a report on behalf of children about."

The minister has already said the portrayal of children in the media might be an issue for the English commissioner to investigate.

The government has so far ruled out banning junk food advertising aimed at children, despite concern that it has a major impact on their eating habits.

Asked how the government would respond if the commissioner recommended such a ban, Mrs Hodge replied: "Don't ask me yet. To pre-judge what the response will be and to pre-judge what the commissioner would say is going too far."