HEALTH activists and pressure groups are pressing for a regulatory ban on junk food television advertising to children despite a decision by Nestle to not market four of its leading products because they fail to meet its own nutritional guidelines.

Nestle is the first advertiser to sign up to an industry code announced last month by the peak body for the $70 billion food industry. The code compels members to advertise healthy food to children under 12 in children's television viewing hours.

Critics have slammed the initiative as ineffective because it fails to take into account the changing viewing patterns and does not include McDonald's, KFC and Hungry Jacks, which are not members of the Australian Food and Grocery Council.

Yesterday they continued to hold out for a government ban on TV ads for junk food and fizzy drinks before 9pm.

Tim Gill, executive officer of the Obesity Society, said he had little faith in self regulation: "We are not moving back from that position of a [9pm] watershed as our preferred option just because they [Nestle] have changed theirs." He added: "It's the start of the process not the end of it."

The Obesity Policy Coalition's spokeswoman, Jane Martin, which also supports the watershed option, said it was a "good thing" that Nestle was responding to community concerns about junk food ads but added: "Regulation is the best way to protect children from commercial exploitation. It needs to apply to everyone and it needs to carry meaningful sanctions."

The food industry's code has come under fire from health campaigners who argue it is too narrow as it only applies to ads placed in children's programs, rather than in programs watched by large numbers of children, such as Australian Idol and Neighbours .

The average television audience of under 12s leaps from 80,000 between 4 and 5pm - when C programs are typically aired - to 500,000 between 7pm and 8pm, according to research by the Australian Communications and Media Authority.

The council said its code will not cover the peak viewing time slot of between 6pm and 9pm, when many children watch TV.

Clare Hughes, food policy officer of Choice , said the concept of "children's programs" was outdated. She said that if four times more children watch The Simpsons , the fact that more adults watch it than children means it won't be covered.