Gravestones to be fitted with microchips in South Africa to stop thieves stealing the marble and granite memorials Memorial Alert is a transmitter installed inside a headstone Sensor will go off it grave is being tampered with Alarm will sound and texts also sent to memorial's owner Company has patent in Britain and hopes technology will spread A company in South Africa is offering to install microchips in tombstones to detect if they're being stolen. Memorial Alert is a transmitter placed inside a headstone which will sound an alarm and send out texts to relatives of the deceased if it detects that a grave is being tampered with. Up to 20 marble and granite tombstones a month are stolen from graves in Johannesburg's 36 cemeteries before being sold on to crooked stonemasons. A company in South Africa is offering to install a sensor into people's gravestone to stop them being stolen The graveyards are already patrolled by security staff and have perimeter fences, but this has not stopped the criminals. Mark Pringle, director Chaldean Trading 9 Ltd, the company developing the technology, said any tampering would set off a loud alarm in the cemetery. If it is disturbed then a loud alarm will sound in the cemetery and text alerts will be send to the memorial's owners He added: 'This in itself should be a fair warning to the perpetrators. Then text messages are sent to the mobile phones of delegated family members and any integrated security companies. Microchips have already been installed in most graves in the city to help relatives find their loved one's resting place in the large, grassy graveyards. Pringle said that the company had considered putting a tacking device into the transmitter, but that it would reduce the battery life and cost too much. He said it would be unlikely that it would be needed as the stones were heavy and difficult to move, and the alarm would be enough of a deterrent. Alan Buff, the manager of Johannesburg City parks, cemeteries and crematoriums, said: 'This is peace of mind for the family. 'Tombstones are the property of the owner which is the family member, and you'll find you cannot insure a tombstone or it's too expensive for many. By doing this, it is insured. The company has a patent in both South Africa and Britain hopes that the technology will spread to other countries after it is trialled in Johannesburg. The alarm will launch in South Africa in January, though a price hasn't been set yet. A transmitter will be placed inside the gravestone and will trigger an alarm to sound if it is being tampered with. The system will also send text alerts to people's families