Labour MP Barry Gardiner has said UK businesses would be at a major “disadvantage” if tariffs were imposed and that Parliament needed to have its say.
The committee stage of the European Union (Notification of Withdrawal) Bill has started today in the House of Commons and runs until Wednesday.
Speaking on CNBC, the MP for Brent North said: “The Government must give real assurance on this point because if tariffs do come into play between ourselves and the rest of Europe then our businesses are going to be at a real disadvantage in terms of their exports.
“What we’ve seen so far is a boost to export business because the value of the pound has dropped so substantially over the past few months.
Barry Gardiner has called on Theresa May to deliver a tariff-free deal
“But we really need to see Government giving that assurance to business that access into the single market will be tariff free.”
Asked what he would like debated on the Brexit bill this week, Mr Gardiner said he wanted to see that protections were not reduced.
He said: “Most important, we need to have parliamentary scrutiny throughout the progress of the negotiations.
“We need to make sure that the Government is going to put in place the protections that we expect in the UK and that they’re not reduced, that’s social protections, environmental protections.
“Really important to people they didn’t think that by voting to leave the EU they were going to lose any of their rights in the workplace or any of their protections in terms of food safety, or food standards or chemicals or so on.
“Absolutely fundamental to this is if we can at a really significant point in the process have the negotiated settlement brought back to the House of Commons so that we as the representatives of the people in Parliament can then say yes, we vote on it at that point.
We really need to see Government giving that assurance to business that access into the single market will be tariff-free
Labour MP Barry Gardiner
“Either we accept the deal or we tell the Government to go back and do a bit better.”
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More than a third of UK businesses are planning to export more goods to Europe over the next five years despite uncertainty caused by the EU referendum, according to a study.
A survey by the British Chambers of Commerce found that almost one in five firms planned to allocate more resources to sourcing products and services from Europe.
Almost one in three of the 1,500 businessmen and women polled said they were looking to increase exports generally as a result of the referendum.
Dr Adam Marshall, the director-general of the British Chambers of Commerce, said: "These results are an important reminder of the fact that it is businesses that trade, not governments."