The mother of a four-year-old boy who was savaged and killed by an illegal breed of dog has written to the Prime Minister calling for a change in the law.

John-Paul Massey suffered multiple injuries when he was attacked by the family pet at his grandmother's home in Liverpool in November 2009.

The boy's uncle Christian Foulkes, 23, admitted owning the animal, called Uno, and was jailed for four months in 2010.

Grandmother Helen Foulkes, 64, admitted one charge of keeping a dangerous dog and was given a four-month jail term, suspended for 18 months, and was banned from owning a dog again.

John-Paul's mother Angela McGlynn told BBC Breakfast that the family believed Uno was an American bulldog and they were not aware of any dangerous dog lists.

She said she had written to the Prime Minister calling for tougher dog laws which would see them muzzled both in public places and in owners' homes.

She said: "They should be muzzled around children under 12 because children over 12 can understand the dog's body language a bit more."

Ms McGlynn added muzzling dogs indoors as well as outdoors was the only way to stop dogs doing "any lasting damage".

She said she had received a reply from David Cameron, who said her proposals would be "taken into consideration".

Communication Workers Union general secretary Billy Hayes said: "We desperately need new dog laws to prevent attacks, promote responsible dog ownership and hold owners of dangerous dogs to account when attacks take place. Thousands of dog-attack victims are currently not protected by the law, including many of our members who have to work on private property to deliver the mail or install broadband lines."