Democrat Hillary Clinton has accused rival Donald Trump of breaking the law by violating the US trade embargo with Cuba, after a report emerged alleging the businessman’s company spent money there without Washington's approval.

Clinton and her team highlighted a Newsweek report that documented a 1998 trip to the communist-ruled island by Trump Hotels & Casino Resorts executives, who were looking into seeking a foothold in the country in the event the United States were to loosen its decades-old embargo.

The magazine said it studied documents that show the Trump company spent at least $68,000 in Cuba when expenditures in the Caribbean country were illegal without US government approval.

It reported that the company did not spend the money directly, opting instead to funnel the funds through a consulting firm - Seven Arrows Investment and Development Corp - with Trump's knowledge to make it appear as if the spending were part of a charitable effort.

The attack comes after Mr Trump highlighted links between Mrs Clinton and Irish businessman Denis O’Brien.

A former Trump executive who spoke to Newsweek on condition of anonymity said the company did not obtain a government license for its spending before the trip.

"Trump appears to have broken the law and acted against our nation's interest, all so he could line his own pockets," Mrs Clinton said in a tweet that included a link to the article on

Instituted in the early 1960s, the trade embargo was designed to starve Fidel Castro's regime of US currency. Despite the recent restoration of diplomatic relations between the two nations, the embargo remains largely in place today.

Facing questions about the report, Mr Trump's campaign manager Kellyanne Conway all-but acknowledged that his company violated the embargo.

"As I understand from the story, they paid money in 1998," she said on the ABC show "The View."

However, Mr Trump ultimately "decided not to invest there," she added, saying the real estate billionaire has remained "very critical" of Cuba and the Castro regime.

Mr Trump's dealings in Cuba could affect the vote in the all-important battleground state of Florida, where more than a million Cuban-Americans live.

Florida's Republican US Senator and onetime presidential candidate Marco Rubio, whose parents fled Cuba, said he was "deeply concerned" about the report.

"I hope the Trump campaign is going to come forward and answer some questions about this," he told ABC's "Capital Games" podcast.

"It was a violation of American law if that's how it happened."