ZURICH  - Switzerland's gold industry on Thursday voiced scepticism about a proposal by the boss of watchmaker Swatch to introduce a levy on gold exports to the United States in retaliation for US tariffs on Switzerland.

US President Donald Trump last week imposed tariffs of 39% on imported Swiss goods, causing shock and dismay in the Alpine republic, a major refining and transit hub for gold.

The US Customs and Border Protection afterwards said Washington might put tariffs on the most widely-traded gold bullion bars in the United States. However, Trump said on Monday that gold would not face tariffs.

Swatch CEO Nick Hayek told Swiss newspaper Blick that Trump's announcement indicated that tariffs on gold would be painful for the US President.

"Now is the time to go on the offensive. Switzerland should order a 39% export tax on gold bars for the United States," Hayek told the paper. "That's where we have to get at him. That's his Achilles' heel."

The Swiss Association of Manufacturers and Traders in Precious Metals (ASFCMP) said that while ideas to better balance bilateral trade were welcome, careful consideration needed to be given to Switzerland's longer-term interests.

"An export tax on Swiss gold destined for the USA would not only harm Switzerland economically, but also damage the reputation of a country that has consistently promoted and defended free trade," ASFCMP President Christoph Wild said.

The Swiss Economy Ministry declined to comment on the proposal, but said the support of business representatives was in general welcome and helped underscore the close economic ties between the US and Switzerland.

Trump justified his 39% tariff by pointing to Switzerland's sizeable trade surplus with the United States. Part of that is due to gold exports.

Hayek said that even if a gold levy failed to move Trump, it would cut the US trade deficit with Switzerland.

"If Trump doesn't give in to our pressure, we'll at least improve the trade balance with the US if the Americans no longer import gold bars via Switzerland," he told Blick.

Switzerland is continuing to hold talks with US officials aimed at lowering the US tariffs.