Citing sources close to the German government, a local newspaper reported that US President Donald Trump had offered "a billion dollars" to secure the vaccine "only for the United States".
The German government promised on Sunday to defend itself against alleged attempts by US President Donald Trump to buy exclusive rights to a German company's research into a vaccine against the coronavirus.
"Germany is not for sale," Economy Minister Peter Altmaier told broadcaster ARD, reacting to a front-page report in Welt am Sonntag newspaper headlined "Trump vs Berlin".
The newspaper claimed that Trump is trying to secure exclusive rights to a potential vaccine against the global health threat that has now killed some 6,000 people, which is being worked on by biotech firm CureVac.
Citing sources close to the German government, Die Welt reported that Trump had offered "a billion dollars" to secure the vaccine "only for the United States".
At a news conference on Sunday, interior minister Horst Seehofer was asked to confirm the attempts to court the German company.
"I can only say that I have heard several times today from government officials today that this is the case, and we will be discussing it in the crisis committee tomorrow," he said.
The report prompted fury in Berlin.
"International cooperation is important now, not national self-interest," said Erwin Rueddel, a conservative lawmaker on the German parliament's health committee.
Christian Lindner, leader of the liberal FDP party, accused Trump of electioneering.
"Obviously Trump will use any means available in an election campaign," he said.
Yet a US official told AFP Sunday that the report was "wildly overplayed".
"The US government has spoken with many (more than 25) companies that claim they can help with a vaccine. Most of these companies already received seed funding from US investors. "
The official also denied that the US was seeking to keep any potential vaccine for itself.
"We will continue to talk to any company that claims to be able to help. And any solution found would be shared with the world."
CureVac, founded in 2000, is based in the German state of Thuringia, and has other sites in Frankfurt and Boston.
The firm markets itself as specialising in "development of treatments against cancer, antibody-based therapies, treatment of rare illnesses and prophylactic vaccines."
The lab is currently working in tandem with the Paul-Ehrlich Institute, linked to the German health ministry.
Last week, the firm mysteriously announced that CEO Daniel Menichella had been replaced by Ingmar Hoerr, just weeks after Menichella met with Trump, his vice-president Mike Pence and representatives of pharma companies in Washington.
"We are very confident that we will be able to develop a potent vaccine candidate within a few months," CureVac quoted Menichella as saying on its website shortly after the visit.
On Sunday, CureVac investors said that they would not sell the vaccine to a single state.
"If we are successful in developing an effective vaccine, then it should help and protect people across the world," said Dietmar Hopp, head of principle investor dievini Hopp Biotech Holding, in a statement.
Economy minister Altmaier welcomed the statement, saying it was a "fantastic decision".
He also pointed out that the government has the power to scrutinise foreign takeovers, saying that "where important infrastructure and national and European interests are concerned, we will take action if we have to."