The European Union has slapped retaliatory tariffs on iconic US products from bourbon to blue jeans and motorbikes in its opening salvo in a trade war with President Donald Trump.

The tariffs, which took effect at midnight, will further fuel jitters on world stock markets that are already alarmed by trade tension between the US and China.

Customs agents across the Europe's colossal market of 500m people will now impose the duty, hiking prices on US-made products in supermarkets and across factory floors.

Brussels imposed the raft of duties on US products worth €2.8bn ($3.3bn) in a tit-for-tat response to Mr Trump's decision to slap stiff tariffs on European steel and aluminium exports.

EU Trade Commissioner Cecilia Malmstrom said this week that the 28-nation bloc was "left with no other choice" but to impose tariffs of its own after the "unilateral and unjustified decision of the US".

Together with US tariffs against Mexico and Canada, the trade battles have raised the spectre of a global trade war, spooking financial markets that fear major consequences to the global economy.

The EU first drew up the list in March when Mr Trump initially floated the 25% tariffs on steel imports and 10% on aluminium, which also target Canada, Mexico and other close allies.

The EU duties come in response to President Trump's stiff tariffs on European steel and aluminium 

The list does not specifically name brands but European Commission chief Jean-Claude Juncker spelled out in March that the EU would target "Harley-Davidson, bourbon and Levi's jeans".

Cranberries, cranberry juice, orange juice, sweetcorn and peanut butter are among the other food products targeted.

The list also hits clothing along with bed linen and men's leather footwear, eye make-up and lipsticks, plus a host of steel products.

See the full list here

Mr Juncker said yesterday that the US decision to impose tariffs "goes against all logic and history".

"Our response must be clear but measured. We will do what we have to do to rebalance and safeguard," he said.

European consumers would be able to find "alternatives", European Commission Vice President for trade Jyrki Katainen said.

"If we chose products like Harley Davidson, peanut butter and bourbon, it's because there are alternatives on the market. We don't want to do anything that would harm consumers," he said.

"What's more, these products will have a strong symbolic political impact."

Transatlantic ties are at their lowest level for many years due to rows over a host of issues including the tariffs, the Paris climate agreement, the Iran nuclear deal and the new US embassy in Jerusalem.

Relations plumbed new depths at the recent G7 summit when Mr Trump abruptly rejected the joint statement and bitterly insulted his Canadian host, Prime Minister Justin Trudeau.

Mr Trump claimed America had been obliged to levy the metals tariffs as it has been exploited as the world's "piggy bank". He is also targeting EU auto imports with a US inquiry now under way.

President Trump's outbursts were the latest in which he has clashed with America's closest allies, even as he has had warm words for autocrats such as North Korean leader Kim Jong un, with whom he had a historic meeting last week, and Russia's Vladimir Putin.

But US Assistant Secretary of State for European and Eurasian affairs Wess Mitchell said yesterday that Mr Trump's approach towards his allies was about "strategic renovation".

"Strengthening the West means making hard decisions today when we initially disagree, rather than continuing to accept the appearance of transatlantic unity for the sake of avoiding disagreement," he told the Carnegie Europe think-tank in Brussels.