A metal hound went on show in Tokyo on Tuesday that can bark but not hear. It can cock its leg but will not leave a mess on the carpet. It can even sulk but will never die - at least, not until its batteries run down.

The dog cannot go for walks outside because rain will damage its electronics

The new toy was unveiled by Sony. Aibo, as it is called, is one of the most advanced "toy" robots yet developed commercially. The company hopes to drive an emerging market in cyber-pets following the worldwide success of tamagotchi.

Aibo was put through its paces in a demonstration which began when it stood up after being patted on the head. It then waved hello with its front paw. Its best trick was catching a pink ball, which it saw using the colour camera installed in its nose.

Robot domination

"The last 10 years of the 20th Century were dominated by personal computers and the Internet," said Sony vice president Toshitada Doi.

Nothing to worry about at this end

"For the next 10 years, until 2010, we are certain that robots with independent movement will be the big thing."

The gleaming metallic puppy has 18 joints producing 250 types of movement. It can play ball, crouch as if urinating and move its head, body and all its legs.

Aibo's owner can praise his dog by touching its head for more than two seconds. A sharp slap on the head is interpreted as punishment and puts the robot into a sulk.

Death function

At the moment, most of the commands are delivered via a remote control, but voice control is being worked on. Aibo, which means partner in Japanese, can make plenty of noise itself, barking, talking and even singing in English or Japanese.

Tickle my tummy

The dog is loaded with sensors including the colour camera, heat sensors, an infra-red range finder, touch sensors, acceleration and speed sensors and a stereo microphone.

A death function was debated by Sony but not included. Aibo can be revived at any time.

The robotic playthings are expensive - 250,000 yen (�1,550) each. They will be on sale on the Internet from 1 June. Sony said it hoped to sell 3,000 in Japan and 2,000 in the United States.