One of the UK's leading waste and recycling companies has been linked to the growing underground trade in e-waste after campaigners uncovered evidence that broken television sets deposited at the firm's facilities were exported to Africa in contravention of regulations designed to stem the flow of electronic waste to developing countries, the Ecologist can reveal.

Merseyside-based Environment Waste Controls (EWC), whose clients are reported to include ASDA, Tesco, Barclays, the NHS and Network Rail, has admitted that electronic equipment from its amenity sites in South London ended up in West Africa after being exported by a third party company and says it has taken steps to prevent this happening in the future.

Campaigners from the Environmental Investigation Agency (EIA) pinpoint the company in a report outlining Britain's role in the global e-waste trade, due to be published next week. The report details the findings of an 18 month investigation into how UK e-waste, much of it toxic, is ending up abroad where it is frequently processed in primitive conditions, posing a threat to the environment and human health.

A BBC Panorama programme to be broadcast on Monday night also investigates the trade and uncovers further evidence of UK electronics waste making its way to West Africa.

As part of the probe, EIA staff visited civic amenity sites in Merton and Croydon where e-waste collection is run by EWC and were told that some of the electrical waste arriving at the facilities was routinely collected by a separate company who exported it to Nigeria and Ghana.

Investigators were told at the Merton amenity site that at least seven tonnes of TVs were being sold to the third party company each week, at a cost of between £1.50 and £2.00 per set.

Under the Waste Electrical and Electronic (WEEE) Resources Regulations 2006, as long as the e-waste arriving at the sites was tested and found to be properly working its export would be permissible.

However, the EIA hid tracking devices inside television sets which had been disabled beyond repair and left them at the Merton and Croydon sites. Several weeks later, according to the group, GPS signals indicated that one TV had been shipped to Nigeria, ending up near a well known e-waste recycling centre, and one was found to have arrived in Ghana.

The EIA says this evidence demonstrates that proper checks were not always being carried out and that the broken TV sets should, under WEEE regulations, have been be sent for recycling in the UK or another developed country, not shipped to West Africa. The campaigners believe this is not an isolated example and say that intelligence suggests that British e-waste is regularly diverted from local authority sites into the black market.

'When disposing of used electrical goods at civic amenity sites, the public has a right to expect that the equipment will be disposed of in accordance with the law,' the group states.

In a statement to the Ecologist, EWC said that it welcomed the EIA report and acknowledged that e-waste from its facilities had ended up in Africa in contravention of WEEE regulations: 'This is unacceptable and EWC has put in place measures to prevent a reoccurrence of this practice and to undertake a full investigation in cooperation with the regulator and relevant authorities. We have instructed all our sub contractors that no electronic equipment deposited at designated collection facilities operated by EWC should leave the UK until further notice.'

EWC, which runs 49 local authority waste sites as well as handling waste and recycling on behalf of the public and private sector, also told the Ecologist that it has not worked with the third party company involved in exporting the faulty TVs to Africa since October 2010.

E-waste is the fastest growing waste stream in the UK, with more than one-million tonnes being generated annually according to some estimates. The UN has stated that global production of e-waste now totals at 50 million tonnes, of which only ten per cent is recycled.

E-waste can be hazardous to the environment and people - computer processors contain a mixture of chemicals and cathode ray tubes fitted in many older style TVs can contain lead. These substances are released when e-waste is stripped down in destination countries, often on vast unofficial waste dumps where workers lack protective clothing and health and safety regulations are poor or non-existant.

In recent years the UK authorities have stepped up efforts to combat the illegal trade in e-waste following growing concern about the scale of the activity.

The Environment Agency has a National Intelligence Team and an Environmental Crime Unit working to tackle the issue and has recently brought prosecutions against a number of individuals involved in e-waste trafficking. There are concerns however that funding for the Agency's e-waste work will be slashed as part of current cost-cutting measures.

Earlier this year the Environment Agency's head Paul Leinster said the body had found evidence of e-waste from government departments forming part of illegal exports.

As the Ecologist revealed in December 2010, the e-waste trade has attracted the interest of highly organised criminal gangs who see it as a lucrative and relatively risk-free activity. The EIA says its investigations have established how a complex network of brokers and middlemen are increasingly facilitating the movement of e-waste, making detection even harder for legitimate companies and the authorities.

'E-waste isn't a new problem and it isn't going away. It's time for the government and enforcement agencies to give this issue the resources and attention it warrants,' EIA's Fin Walravens said.

• Track My Trash - Panorama - is broadcast Monday May 16th 8.30pm BBC One