A coalition of 12 US states sued US President Donald Trump's administration over "illegal tariffs" in the US Court of International Trade in New York.

Attorneys general of Arizona, Colorado, Connecticut, Delaware, Illinois, Maine, Minnesota, Nevada, New Mexico, New York, Oregon and Vermont on Wednesday filed the lawsuit to seek a court order to block the Trump administration from enacting the tariffs.

The lawsuit said the policy has left the national trade policy subject to Trump's "whims rather than the sound exercise of lawful authority," asking the court to declare the tariffs illegal and to block government agencies and officers from enforcing them, Xinhua news agency reported.

It noted the US President can only invoke the Emergency Act when there is an "unusual and extraordinary threat" from abroad.

"By claiming the authority to impose immense and ever-changing tariffs on whatever goods entering the US he chooses, for whatever reason he finds convenient to declare an emergency, the President has upended the constitutional order and brought chaos to the American economy," the legal action said.

"Congress has not granted the President the authority to impose these tariffs and therefore the administration violated the law by imposing them through executive orders, social media posts, and agency orders," New York Attorney General Letitia James' office said in a statement.

"His tariffs are unlawful and if not stopped, they will lead to more inflation, unemployment, and economic damage," said James.

"President Trump's reckless tariffs have skyrocketed costs for consumers and unleashed economic chaos across the country," New York Governor Kathy Hochul said in a statement on Wednesday.

In response, White House spokesperson Kush Desai said the administration "remains committed to addressing this national emergency that's decimating America's industries and leaving our workers behind with every tool at our disposal, from tariffs to negotiations".

On April 2, Trump signed an executive order at the White House, invoking the International Emergency Economic Powers Act to declare a national emergency and impose so-called "reciprocal tariffs" on all US trading partners.

The move triggered strong opposition from the international community and within the US, leading to significant turmoil in the financial markets.