Sigmar Gabriel - leader of the center-left Social Democratic Party now in coalition with the dominant Christian Democratic Union - criticized Merkel for her enthusiastic support for a sweeping EU-US free trade deal now under scrutiny by European and US lawmakers.

Gabriel, who also serves as economy minister, said Merkel was "wrong" about the benefits of the sweeping pact that would harmonize regulations between the US and EU.

Critics warn the deal would undermine environmental and labor protections by allowing transnational corporations to challenge domestic laws and regulations in special tribunals on the grounds that they hurt profits.

Gabriel told the regional newspaper group RND that his SPD "doesn't wish to be part of a bad deal," as he warned against a hastily negotiated agreement on the Transatlantic Trade and Investment Partnership (TTIP).

Growing public skepticism

Thousands have protested in Germany against TTIP

During a meeting in Japan this week, leaders of the G-7 nations - the US, Germany, Japan, Britain, Italy, France and Canada - expressed their support for TTIP, as long as it is "ambitious, comprehensive, high standard and mutually beneficial".

US President Barack Obama used a recent trip to Europe to tout the economic benefits of TTIP, which would create a free trade zone encompassing 850 million people.

But Gabriel said Merkel "was wrong to say, in the euphoria of Obama's visit to Germany, that we will be able under all scenarios to conclude negotiations this year."

The next round of TTIP talks is set to take place next month as public skepticism remains high.

Some 70 percent of Germans polled this month said they believed the TTIP would bring "mostly disadvantages." Tens of thousands of people rallied last month to protest the TTIP during Obama's visit to a trade fair in Hanover.

jar/gsw (AFP, Reuters)