Hong Kong's leader laughed off US sanctions against him Tuesday as he defended his government's decision not to act against a superyacht reportedly owned by a Kremlin ally.

The Nord -- a $500 million luxury vessel linked to Russian billionaire Alexei Mordashov -- arrived in the Chinese territory's waters last week.

Mordashov is among the oligarchs close to Russian President Vladimir Putin who have been targeted by Western sanctions following Moscow's invasion of Ukraine.

On Saturday the United States warned Hong Kong could damage its business hub reputation after the city said it would not enforce sanctions on the superyacht.

Hong Kong chief executive John Lee himself is one of multiple Chinese officials sanctioned by the United States in 2020 for their roles in cracking down on political freedoms in the city.

Banks and other companies risk losing access to the US-dominated global markets if they do business with sanctioned officials, with Lee's predecessor revealing she had to take most of her salary in cash as a result.

When asked about the impact of US sanctions against him on Tuesday, Lee told reporters: "It is a very barbaric act and I am not going to comment on the effect of such barbaric act."

"We will just laugh off the so-called sanctions."

Some sanctioned oligarchs have had their luxury yachts seized in places such as Spain and Fiji, but Hong Kong said Friday that while it implements UN sanctions, it cannot enforce those imposed "unilaterally" by countries or blocs.

Lee repeated that argument on Tuesday, describing US and European sanctions as having "no legal basis".

"We will comply with any UN resolution on sanctions because Hong Kong has the legal basis to enforce it," he said.

But he added: "We cannot and will not do anything that has no legal basis".