Anti-TTIP activists have submitted a 3 million-signature petition to the European Commission in London and Brussels in a bid to halt secret trade negotiations between the EU, US and Canada.

The petition, believed to be one of the largest ever compiled, calls for an immediate end to Transatlantic Trade and Investment Partnership (TTIP) negotiations.

Some 500,000 people in the UK signed the petition, alongside millions of EU citizens.

It cites concern over the lowering of environmental, consumer and employment protections and the deregulation of public services such as water as a result of TTIP.

Campaigners also highlight the controversial investor-state dispute settlement (ISDS), a clause that would pave the way for private firms to sue governments in cases where government policies threaten a company’s profits.

In March, a British parliamentary committee published a scathing attack on TTIP in which it called on the government to produce more convincing evidence in favor of the deal.

There are also fears powerful tobacco companies could use TTIP to sue governments that attempt to legislate in the public interest, according to heavily redacted European Commission documents released last month.

The petition also calls for a halt to the Comprehensive Economic and Trade Agreement (CETA) between the EU and Canada, a parallel trade deal currently awaiting ratification.

Activists argue CETA includes a similar ISDS clause that will enable corporations to take legal action against governments which seek to restrict their profit.

“We want to prevent TTIP and CETA because they include several critical issues such as investor-state dispute settlement and rules on regulatory cooperation that pose a threat to democracy and the rule of law,” the petition states.

“We want to prevent lowering of standards concerning employment, social, environmental, privacy and consumers and the deregulation of public services (such as water) and cultural assets from being deregulated in non-transparent negotiations.”

The petition was organized as a European Citizens Initiative (ECI) by a group of NGOs and charities, including War on Want and Global Justice Now, within the Stop TTIP umbrella group.

A spokesperson for Stop TTIP said the huge number of signatures meant the petition must be taken seriously by EU officials.

“Stop TTIP collected more signatures than any other European Citizens’ Initiative so far – we demand that the European Commission pays heed to the protest against CETA and TTIP. We want the TTIP negotiations to be stopped and the ratification of CETA to be rejected,” says Michael Efler, a member of the Stop TTIP citizens’ committee.

Political scientist Susan George challenged the EU to be more transparent about TTIP, which has been negotiated in behind closed doors.

“In one year alone we united three times as many people than needed for an ECI to be successful according to EU rules,” she said.

“This great success shows how strong opposition to TTIP and CETA has grown throughout Europe. If there is just a grain of truth to the promises for transparency and citizen consultation, the EU institutions must organize a hearing in Parliament and the Commission must take action to stop the treaties.”