Talks aimed at setting up a U.S.-European free trade zone have run aground because of intransigence on Washington's part, a top German politician said Sunday.

"In my opinion the negotiations with the United States have de facto failed even though nobody is really admitting it," said Sigmar Gabriel, German vice chancellor and economy minister, in an interview with the broadcaster ZDF on Sunday.

The Obama administration and the 28-member European Union have been in talks to set up the Transatlantic Trade and Investment Partnership, or TTIP, which would be the world's largest free trade zone.

But negotiations have reportedly stalled because of the unexpected decision by Britain to leave the EU and because of growing public opposition to trade agreements on both sides of the Atlantic.

Gabriel said the U.S. and the EU haven't agreed on a single item out of 27 chapters being discussed, despite 14 rounds of talks, and he said Washington was "angry" about a similar trade agreement struck between Canada and the EU. He said Europe "must not succumb to American demands."

Neither the European Commission nor the U.S. Trade Representative's office had any immediate response to the comments.

On the record, U.S. and European officials say they are continuing to move forward with talks and stress the importance of the TTIP to their economies.

"It's our job to make sure that we adequately inform people about the facts of how TTIP will actually work for the people of Europe," U.S. Secretary of State John Kerry said at a press conference in Brussels last month.

"It will protect jobs, it will protect their regulatory rights, protect their abilities with respect to labour and the environment," he said.

German Chancellor Angela Merkel said last month that the TTIP is "absolutely in Europe's interest."

"We are determined to continue these negotiations," added EU Trade Commissioner Cecilia Malmström. "They are important for Europe, for our economy, for our jobs, for our business people, for our consumers, and it makes a lot of sense to do it even (without Britain)."

But behind the scenes, there have been signs of trouble in the talks.

Last month, Agence France-Presse quoted diplomats as saying that talks may be suspended until after the U.S. elections in November, as well as elections in France and Germany next year.

French Prime Minister Manuel Valls said TTIP would be "a breeding ground for populism." And in the U.S., Republican Senate Majority Leader Mitch McConnell has said, "By any objective analysis this is, shall I say, a down period for trade agreements around the world."

Britain's decision to leave the EU had only made the negotiations tougher, as The Economist recently reported:

"Though the Brexit vote was shaped by concerns about the free movement of labour, rather than of goods and services, the appetite for new trade deals was already weak."Copyright 2016 NPR. To see more, visit http://www.npr.org/.