LONDON, Feb. 26 (Xinhua) -- British Foreign Secretary Boris Johnson claimed Monday that Britain would become a colony of the European Union (EU) under a potential trade deal outlined Monday by Labour leader Jeremy Corbyn.

The Brexit-supporting cabinet minister joined a chorus of what was divided opinion after Corbyn, leader of Britain's main opposition party, outlined Labour's Brexit strategy.

Corbyn, in a key-note speech in Coventry, said Labour would seek to negotiate a new comprehensive UK-EU customs union to ensure that there are no tariffs with Europe and to help avoid any need for a hard border in Northern Ireland.

Under current EU rules, membership of the customs union and the European single market would mean Britain having to accept free movement of people across the 500-million population bloc. Prime Minister Theresa May has consistently rejected such a deal.

The Guardian, in its commentary, said Corbyn has not given a speech on Brexit for about a year, and in the House of Commons he often avoids the subject.

"But today's speech was well-crafted and substantial, and could potentially have a decisive impact on UK Brexit policy," said the commentary.

Johnson did not mince his words, attacking Corbyn's proposals: "Crumbling Corbyn betrays Leave voters, and all because he wants to win a commons vote. Cynical and deluded."

Johnson said remaining in a customs arrangement would make Britain a colony of the bloc.

International Trade Secretary Liam Fox said: "Labour's confused policy would be bad for jobs and wages, it would leave us unable to sign up to comprehensive free trade deals, and it doesn't respect the result of the referendum. This is another broken promise by Labour."

Carolyn Fairbairn, Confederation of British Industry (CBI) Director-General, said the Labour leader's commitment to a customs union will put jobs and living standards first by remaining in a close economic relationship with the EU.

"It will help grow trade without accepting freedom of movement or payments to the EU," said Fairbairn.

"Growing trade is not an 'either or' question... Many thousands of ambitious UK firms are looking to break into new markets. These companies need government to focus on making access to markets simpler, not putting up barriers to our most important trading partner."

Fairbairn added that businesses have their eyes wide open on Labour's overall rhetoric on re-nationalisation.

She said: "If Labour turns its back on good collaboration between the government and the private sector -- putting vital sectors solely in the hands of politicians -- public services, infrastructure and taxpayers will ultimately pay the price. The CBI will continue to engage with the Labour Party to find better solutions to the shared challenges we face."

Stephen Martin, director general of the Institute of Directors (IOD), said Labour had widened the debate and manufacturers would be particularly pleased that a customs union was staying on the table.

Adam Marshall, Director General of British Chambers of Commerce, said: "Corbyn's position on the customs union, like the governments, is more political than practical for business. The priority must be to delve far more into the detail and negotiate pragmatic deal on customs and regulatory recognition."

Veteran Labour MP Frank Field described Corbyn's UK-EU customs union plan a non-starter, saying Brussels would never go along with such an idea that flies in the face of its long-standing rules.

Downing Street was saying little in response to Corbyn's speech, with a one-line comment from a spokesperson for Theresa May.

"The government will not be joining a customs union. We want to have the freedom to sign our own trade deals and reach out to the world," said the spokesperson.

The focus will now switch to a keynote speech by May due Friday which will focus on the government's vision of a new UK-EU post-Brexit relationship.