Theresa May should be forced to seek parliamentary approval for any trade deal with the US, Australia or others to make sure health, environmental and business standards are maintained, Caroline Lucas, the Green co-leader, will say on Friday.

Speaking at the Green party spring conference in Liverpool, Lucas will demand proper oversight of trade deals, arguing it is not good enough for them to be laid before parliament as statutory resolution that can be waved through without detailed scrutiny by MPs and peers.

There is likely to be considerable opposition to some elements of trade deals, given the controversy over the EU’s attempted TTIP deal with the US which critics said could have led to further privatisation in the NHS and allow big corporations to sue the government for damaging their commercial interests.



That deal is now dead following the election of Donald Trump, but May and her ministers, including Liam Fox, the international trade secretary, have signalled their intention to strike bilateral trade agreements as soon as possible.

Nick Clegg, the former deputy prime minister, is among those warning that a trade deal with the US could lead to lower environmental standards, such as chlorine-washed chicken being imported to the UK.

Lucas said there would need to be detailed line-by-line scrutiny of any trade deals signed, debates at the beginning of the process and votes at the end.

“Britain is about to go through a period of monumental change – not least when it comes to our trade deals,” she said. “We know the risks associated with bad deals – a race to the bottom on regulations, companies suing democratically elected governments and the outsourcing of jobs.

“We’re calling on the British government to give parliament proper oversight of any new deals – whether that’s the touted deal with Trump or any new deal with Europe. At present deals are snuck through without a proper debate or yes/no vote – it’s time for an urgent democratic upgrade.”

Alongside co-leader Jonathan Bartley, Lucas will also promise that their party will oppose the “rightwing coup” that has taken place in the UK following Brexit and May’s accession to the Conservative leadership.

“I believe in the British people. Which is why I do not believe they voted for the extreme form of Brexit adopted by this government,” Bartley will say. “I don’t believe they voted to turn away from European values, from democracy or the rule of law. Or to cosy up instead to dictators and one-party states in return for dodgy trade deals.”

The party opposed the triggering of article 50 and continues to support free movement and a close relationship with the EU.