BERLIN, April 23 (Xinhua) -- German Chancellor Angela Merkel called for a strengthening of the World Trade Organization (WTO) on Monday ahead of a planned official visit to the U.S.

Speaking before a delegation of German and Mexican businessmen at the Hanover Trade Fair, Merkel rallied supporters of free trade to defend and expand the authority of the Geneva-based WTO.

"We know that we must also strengthen the WTO as such alongside bilateral agreements," the chancellor said.

"We need a new multilateral agreement," Merkel added. She warned that the failure to successfully conclude a WTO round of negotiations since the so-called Uruguay round in 1994 was evidence that the existing system for rules-based free trade and related dispute settlement had begun to totter.

Merkel is scheduled to arrive in Washington on Friday for talks with President Donald Trump and is likely to raise the issue of growing U.S. protectionism.

A special exclusion for the European Union (EU) from recently-imposed U.S. tariffs on steel and aluminum imports expires on May 1, with Brussels threatening to file a lawsuit before the WTO unless a permanent solution is found.

Speaking in Hanover, Mexican President Enquire Pena Nieto further demanded a swift and mutually-agreeable reform of the North American Free Trade Agreement (NAFTA) which was first signed by the U.S, Canada and Mexico in 1994. Trump has repeatedly described NAFTA as a "disaster" and threatened to withdraw from the agreement.

In the meanwhile, the EU and Mexico have reached an agreement on the key parameters of a new bilateral trade pact.

Merkel described Mexico as a reliable investment partner on Monday and noted that the annual volume of trade between Germany and the Latin American country had grown to more than 20 billion euros (24.5 billion U.S. dollars) in 2017.

The German chancellor emphasized in this context that growth in Mexican exports to Germany, at 44 percent, had significantly outpaced that of German exports to Mexico, which stood at 16 percent.

"This is exactly the right direction needed to gradually achieve equilibrium in the international balance of trade which we too have a strong interest," she said.

Berlin has repeatedly been chastised by Trump, as well as the Washington-based International Monetary Fund (IMF) for allegedly contributing to global imbalances with its export-driven growth model.

The IMF argues that permanent surpluses above six percent of gross domestic product (GDP) endanger economic stability because they imply corresponding deficits and a build-up of international liabilities in other countries.

Commenting on the basic agreement on a new trade relationship between the EU and Mexico, the Association of German Chambers of Industry and Commerce (DIHK) described the development as "enormously important" for Germany's economy.

"This is a much-needed signal for more economic cooperation in our times. The agreement shows that transatlantic trade can be developed positively," DIHK international trade export Volker Treier argued.