Heart bypasses are heavily invasive and risky to the patient.

But doctors cannot easily perform such operations through a "keyhole" in the chest - or endoscopically - which poses less risk.

Attachments replicate the surgeon's movements with more precison

The robot, developed by German surgeons, means doctors can carry out complex procedures with less risk of making a wrong move.

It is the latest in a series of innovations in recent years to bring robot technology into the operating theatre.

In February doctors in Belgium announced success with a similar robot that could be operated by surgeons over telephone lines.

And doctors in the UK are evaluating a technique of fixing swollen arteries around the heart by inserting equipment into the artery by the groin and moving it up to where it is needed.

Professor Reichenspurner has been testing teh equipment

Such methods provide an alternative to open-heart surgery, and, because only a small incision is needed, there is less risk and the patient does not have to spend as long in hospital.

The German robot is so precise it can stitch together veins and arteries around the heart by remote control.

Professor Reichenspurner, who has been testing the equipment on pigs' hearts, said: "Basically it allows endoscopic microsurgery on the heart.

"This was not possible and was not done before because your hand gets very imprecise when you work with a long instrument through a small hole in the chest."

An interior view is available

The surgeon moves the hand controls, and the robot translates his actions to extremely accurate movements inside the chest.

The robot has three arms - two operated by the surgeon's hands and a third that carries a voice-controlled camera.

This allows the surgeon to see what is going on inside the enclosed space of the chest cavity.

Patients who undergo a robot-assisted operation are expected to return to normal life within two weeks of what was once a life-threatening operation.