US President Donald Trump handed German Chancellor Angela Merkel a bill for more than $300 million (277.6 million euros) for Berlin's failure to meet NATO's defense spending target of 2 percent of GDP, British newspaper "The Sunday Times" reported on Sunday, citing an unnamed German government official.

The same official told the British newspaper that Merkel had not responded to the invoice.

"The concept behind putting out such demands is to intimidate the other side, but the chancellor took it calmly and will not respond to such provocations," the official said.

White House spokesman Michael Short denied the incident occurred, telling US broadcaster CNBC and other media outlets that the report was "false."

Trump reportedly requested White House aides to calculate the amount by totaling the difference between Berlin's defense spending and NATO's 2 percent of GDP target from 2002, when former German Chancellor Gerhard Schröder pledged to increase defense expenditure.

The "owed" amount allegedly included interest for failure to meet the target.

Trump has claimed that NATO countries rely on US defense to protect them, and that Washington is effectively owed for this protection. But US allies in NATO have insisted that's not how the transatlantic alliance works.

'No account where debts are registered'

In the wake of Merkel's official visit to the US, Trump argued forcefully that Germany owed vast amounts to Washington for its protection.

"Germany owes vast sums of money to NATO and the United States must be paid more for the powerful, and very expensive, defense it provides to Germany," the US president said in two tweets.

German Defense Minister Ursula von der Leyen issued a statement in the wake of Trump's allegations, saying: "There is no account where debts are registered with NATO."

Meanwhile, Germany is the second-largest funder of NATO's civil and military budgets, comprising nearly 14 percent of common-sharing budgets and programs in the alliance.

The UK and France trail behind Washington and Berlin, providing 10.6 percent and 9.8 percent, respectively.