Foreign Secretary William Hague will discuss the United States' position on the Falkland Islands with John Kerry following reports that Washington will not recognise the result of next month's referendum.
The vote is expected to underline the islanders' determination to remain a British overseas territory in response to Argentina's claims over sovereignty.
Mr Kerry will make his first visit to the UK as secretary of state next week and Foreign Office sources said the Falklands would be one of the issues raised by Mr Hague with his American counterpart.
The state department said last month it recognised "de facto United Kingdom administration" of the Falkland Islands but "takes no position regarding sovereignty".
When the public vote was announced last year, a state department official said: "We will not speculate on a referendum that has not taken place. Our position remains one of neutrality."
A Foreign Office spokeswoman said the UK Government is in "regular touch" with the US on the issue of the Falklands.
A spokeswoman said: "The US position has not changed. The US does not support Argentina's sovereignty claims. The US recognises the UK's administration of the Falkland Islands, but takes no position on sovereignty.
"We are, of course, in regular touch with the US on this issue, as on so many others. And we expect that dialogue to continue.
"Unlike Argentina, the UK has no desire to bring third parties into a bilateral issue. Our position on supporting self-determination for the Falkland islanders is underpinned by the United Nations Charter, which is binding on all UN members."