Experts said the seizures were part of a "tsunami" of discarded consumer goods being exported from Australia and piling up overseas, contributing to major health and environmental hazards.

The Department of the Environment confirmed 21 containers of e-waste – old electronics such as televisions, computers, printers and mobile phones – had been intercepted without hazardous waste permits since 2010.

Most containers were destined for ports in west Africa and Asia, with the three shipments stopped so far this year heading to Nigeria, Ghana and China.

The Environment Department said the cargo was stopped and the exporters told to dispose of the hazardous waste. But there is yet to be a prosecution for illegally shipping e-waste overseas.

The Australian Customs and Border Protection Service has also admitted it does not keep records of cases referred to the Environment Department for investigation.

Former federal government adviser Mariann Lloyd-Smith, from the National Toxics Network, said the seizures were the "tip of the tip of the iceberg".

"E-waste is one of the tsunamis of waste that we're facing and Australia has a phenomenal contribution," she said. "We have had specific incidents, particularly in Ghana, where we know of shipments from Australia."

In 2008 almost 17 million electronic devices were discarded by Australians, a number that is expected to swell to 44 million by 2028. It is estimated only about 4 per cent of Australia's hazardous waste - including e-waste - is recycled.

Australia's National Television and Computer Recycling Scheme currently processes about a third of the nation's discarded TVs and computer equipment (40,813 tonnes) and has a target of 80 per cent by 2022. But most e-waste is still dumped in landfill and an unknown quantity is shipped overseas.

The United Nations Environment Program has warned that without a global effort to boost e-waste recycling, many developing countries face the prospect of "hazardous e-waste mountains".

West Africa and Asia have already been singled out as hot spots for e-waste, which contains toxic chemicals including lead, mercury and cadmium that leach into the soil and contaminate the air.

There is also evidence the trade fuels child labour, with locals picking through e-waste dumps in search of valuable minerals found inside the electronics.

A recent study of 300 children near an e-waste dump in Kenya found about half had respiratory problems and one-third had blood abnormalities indicating heavy metal poisoning.

Jeff Angel, of Total Environment Centre, said not enough was being done to stop Australia's e-waste scourge.

"It just shows that we have a half-hearted regulatory regime," he said. "The main motivation for exporting e-waste is that it's cheaper than recycling it or storing it. The question has to be asked about who's collecting it."

Industry sources reported being asked to sell e-waste so it could be sent offshore and said some recycling companies were involved in the illegal trade.

"There are a lot of illegal shipments going on within the [recycling] industry," said Graham Muir, senior e-waste manager at Sims Recycling Solutions.

Mr Muir said he was contacted "at least every week" about selling e-waste. "They're looking for bulk volume, quite specifically PCs, televisions, monitors."

Mr Muir said a recent email inquired about buying 1000 printers to be shipped to Pakistan. "There's a lot of requests that come in like this...quite clearly to export to Pakistan, China, India."

Geordie Gill, 1800Ewaste founder, said calls from people wanting to buy e-waste had dropped since the rollout of a national recycling program for televisions and computers, but the problem was still a "massive issue".

"A lot of them do state that they're sending it overseas," he said. "They're not trying to hide it. No one's getting punished for it so it's not really illegal."

Dr Lloyd-Smith, who has witnessed e-waste stockpiles in Third World countries, said Australians should take steps to ensure their old electronics were handled responsibly.

"We replace our white goods and electronics very regularly and have the attitude that if we want to dump, we have the right because we're a developed country," she said.

Where the e-waste was headed:

Hong Kong 5

Nigeria 3

Malaysia 3

Ghana 2

Vietnam 2

Pakistan 2

China 1

Sierra Leone 1

Republic of Korea 1

United Kingdom 1

Containers intercepted between January 2010 and September 2014. Source: Department of Environment