There have also been allegations, first reported by Italy’s La Repubblica newspaper, that a letter endorsing a business plan for the development of the monastery was fake.
Mr Harnwell has strenuously denied reports that fraudulent documents, presented to the Gibraltar subsidiary of a Danish bank, were used to win the lease.
But Lars Jensen, the managing director of Jyske Bank in Gibraltar, told The Economist last week: “It is a fraudulent letter, put together by I don’t know who.”
In early May, Mr Harnwell told The Telegraph that the allegations were a plot by “the hard Left” to discredit his association and Mr Bannon.
The accusation that any documents were counterfeit was “frankly bizarre”, he said.
“Why would we even bother going to the trouble of counterfeiting such a letter that we could have easily asked any bank to furnish? It just doesn’t make any sense,” he said.