"Deposits" of gold in electronic waste are around 50 times richer than ore mined from the ground, according to figures put forward by recycling experts on Friday.

The amount of precious metal junked in cellphones, laptop computers, PCs and other electronic goods is rising hugely but very little of it is recovered, they said.

More than 320 tonnes of gold, worth more than $16 billion (13 billion euros), and 7,500 tonnes of silver, worth $5 billion, are used annually in electronic products, the report by the United Nations University and the Global e-Sustainability Initiative (GeSI) said.

For gold, just 10-15 percent is recovered, while the rest goes unspotted or is wasted in the crude recovery methods used in backyard shops.

Tonne for tonne, e-waste has 40-60 times more gold than ore, according to the estimate.

It suggested there are around 200 grammes (seven ounces) of gold in a tonne of circuit boards and 300 grammes (10.5 ounces) in a tonne of cellphones, compared with 5 grammes (0.17 ounces) in a tonne of ore.