The head of the UN agency responsible for promoting trade across the developed world has warned that a tariff war between the EU and U.S. would drag the global economy backwards.

"It means straight into a recession," Arancha Gonzalez, the Executive Director of the International Trade Centre (ITC), said in an interview with CNBC Wednesday after meeting with European Commission officials in Brussels.

"All of this is pointing in one direction. If we keep digging into that same hole, we will be looking into a major recession."

U.S. tariffs on $7.5 billion worth of European products are currently scheduled to take effect on Friday Oct. 18, after World Trade Organisation (WTO) arbitrators authorized the U.S. to take countermeasures against the EU to remedy decades of illegal government subsidies to the aircraft manufacturer Airbus.

The European Commission, which oversees trade policy for the EU, has repeatedly said that it would like to enter negotiations with the United States to settle the dispute, without resorting to tariffs.

Back in May, the EU had published its own preliminary list of American products, worth $20 billion, that could face future retaliatory tariffs. Earlier this month the EU's new designated trade commissioner Phil Hogan told European lawmakers in his confirmation hearing that the trading bloc must be prepared to "stand up for itself."

On Monday after the WTO's formal adoption of the arbitrators' ruling on Airbus, the U.S. ambassador to the WTO, Dennis Shea, said the Trump administration expected that it would only be after the enactment of the countermeasures on Friday that the E.U. would "agree to a genuine cessation of its WTO-inconsistent subsidies and the adverse effects that flow from them."

Gonzalez argues that - based on all empirical evidence - this is entirely the wrong approach.

"What we fundamentally know is that tariffs do not solve the underlining problem that exists in international trade," she told CNBC.

"What would make sense is everybody that produces planes sitting around the table to figure out how do they strengthen anti-subsidies rules, how do they ensure fairer competition in the aircraft sector - given that they all cheat at the moment."