The government was thrown into the spotlight on Monday over its failure to impose measures to crack down on the owners of dangerous dogs.
Proposals promised included extending the Dangerous Dogs Act to cover private property, which means owners could face prosecution if their dog attacks someone lawfully on their premises.
Millions of dog owners in England will also be forced to pay to fit their pets with microchips detailing who the animals belong to.
But campaigners accused ministers of "dragging their feet" after Environment Minister Jim Paice revealed the plans would be subjected to a consultation, rather than put into action.
Communication Workers Union (CWU) general secretary Bill Hayes, whose union has spearheaded the Bite Back campaign to strengthen the law, said: "We've had a comprehensive consultation and there's cross-party support - now we need action.
"It's about time the law bit back to protect innocent dog attack victims."
There have been five fatal dog attacks in homes since 2007 - four of them on children - and hospital admissions for serious dog bites have more than doubled over the past decade, according to Defra's own figures.
The union released figures at its conference in Bournemouth on Monday that revealed 70 per cent of dog attacks on members happen on private property where the current law does not apply - effectively treating postal workers as "criminal trespasser."
Around 6,000 members across Britain were attacked every year - or 12 a day - and nearly 400 had taken time off sick in the past year alone after suffering severe injuries while on delivery rounds.
Battersea Dogs & Cats Home and the Dogs Trust, which supports the CWU's campaign, said the government was "just tinkering around the edges" rather than looking at effective and preventative measures.
"With scant detail from the government on how this scheme will be enforced, will it make any difference?" said Battersea Dogs & Cats Home chief executive Claire Horton.
Angela McGlynn, whose four-year-old son John-Paul Massey was mauled to death by an illegal breed of dog in 2009, said the microchip plans would not have saved his life.
"The government should be looking at prevention," she told BBC Breakfast, suggesting measures such as forcing owners to keep dogs identified as potential problem animals on a lead or muzzled in public.
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