The US government said Monday it is immediately placing a 17 per cent duty on most fresh Mexican tomatoes after negotiations ended without an agreement to avert the tariff. Proponents said the import tax will help rebuild the shrinking US tomato industry and ensure that produce eaten in the US is also grown there. Mexico currently supplies around 70 per cent of the US tomato market, up from 30 per cent two decades ago, according to the Florida Tomato Exchange.

Robert Guenther, the trade group's executive vice president, said the duty was "an enormous victory for American tomato farmers and American agriculture". But opponents said the import tax will make tomatoes more expensive for US consumers. Mexico's Economic Secretary Marcelo Ebrard said the government would continue looking for a way to once again suspend the tariff, part of ongoing negotiations between the two trading partners. In a statement Monday, he wrote that the move would "only affect the pockets of American consumers".

"It's unfair and against not only Mexican producers, but on the American industry. The ground that Mexican fresh tomatoes has gained in the US is because of the quality of the product, not from unfair practices," he wrote. Mexican greenhouses specialise in vine-ripened tomatoes, while Florida tomatoes are typically grown in fields and picked green. Tim Richards, a professor at the Morrison School of Agribusiness at Arizona State University, said US retail prices for tomatoes will likely rise around 8.5 per cent with a 17 per cent duty.