Rashid Rullah yesterday remained in a critical condition in hospital after what police said appeared to be a "tragic accident" in Birmingham on Sunday.

The boy's grandfather said Rashid was accidentally shot by his five-year-old sister when their father, who had been using the rifle for target practice, turned his back on the children to answer his mobile phone.

Yesterday the Gun Control Network (GCN) said such tragedies were "not merely 'accidents'," but were preventable incidents.

The organisation, which campaigns for tighter controls on guns of all kinds, called for legislation to register airguns and their owners, and make them liable for the misuse of their weapons.

It said in a statement: "The tragic shooting of the toddler Rashid Rullah highlights once again the terrible consequences of the "boys' toys" culture surrounding airgun ownership.

"This culture results in easy access, casual regard and non-accountability.

"Because airguns are not treated as "real" weapons they are not thought worthy of registration or regulation.

"They are not taken seriously."

The GCN said airguns were responsible for about half of all firearms offences and more than a quarter of all serious firearms injuries.

It said children had picked up air weapons left lying around and other children, often siblings or friends, had been killed, blinded or injured.

"The adults who own these guns are rarely held to account," the GCN said.

"There is no law requiring them to store their weapons safely, nor is there any record of ownership."

The father of 12-year-old Mitchel Picken, who was killed in 2006 as his friends played with an air weapon, also joined the call for stronger controls.

Andrew Picken said: "The Government cannot hide behind recent changes in legislation, which failed to take the airgun problem seriously enough and make owners responsible for storing their weapons safely.

"Airguns and their owners could be registered, and they should be."

Angela Lawrence, of Mothers Against Violence, said of Sunday's shooting: "It just highlights how vulnerable people are in the presence of weapons and guns.

"People have died as a result of airgun pellets, so they are dangerous weapons if not used in a safe environment."

Rashid was playing with his five-year-old sister in the family's garden in Washwood Heath, Birmingham, on Sunday evening while their father, Bakht Zaman, used the air rifle for target practice.

But shortly before 7pm, the 29-year-old handyman turned his back on the children to answer his mobile phone, the boy's grandfather, Bakht Rammand, said. As Mr Zaman did so, he left the gun loaded in preparation for his next shot.

Mr Rammand, 48, said it was then that the boy's sister, Asna Almas, picked up the gun and accidentally shot the toddler in the back of the head.

He said: "Everybody's in shock. There are no words to describe it really."

Surgeons have been unable to operate on the boy at Birmingham Children's Hospital, where he remains unconscious.