A forgotten 172-year-old treaty signed between Spain and the South American country gives it sovereignty rights over the British colony, they say.



Uruguayan architect Juan Ackermann, one of the two authors of the book, insisted: "Legally, the islands are ours."



Co-author Alfredo Villegas, an Argentine engineer, added: "For me, as an Argentine, it was very difficult to come to terms with this."



The book, whose title translates into English as 'The Falkland Islands – Are They Uruguayan?' argues colonial Spain controlled the region's seas, islands and coastline from naval bases in Cuba, Peru and the Uruguayan capital Montevideo.



Mr Ackermann said: "No one remembers a 1841 treaty signed between Spain and Uruguay.



"In that document, Spain cedes it the naval base's powers.



"Seventeen years later, Spain did the same with Argentina, but it couldn't give it something it's already given another. That is a very strong argument in favour of Uruguay."



A 1972 international agreement on the Antartic confirmed Uruguay as the rightful owner of the Falklands because it was based on the 1841 treaty, Mr Villegas added.



He told an interviewer: "It was signed first in the Uruguayan senate and then in the Argentine senate.



"The basis of that signature is the 1841 treaty.



"When the Argentine legislators signed, they were recognising that agreement.



"It's obvious they didn't read what they signed."



One option for Uruguay now is to do nothing and let Argentina and Britain carry on their war of words over the islands, the authors argue.



But they also claim Uruguay would be within its rights to start negotiations with the UK and Argentina about proposals to divide up the disputed territory.



International analyst Juan Luis Gonzalez-Perez described the book on Thursday as a "historical curiosity" but quashed the idea Uruguay had any sovereignty claim over the Falklands.



He insisted: "Uruguay has never shown any type of interest in that area and it would be a triviality for it to now make any sovereignty claim.



"The United Nations recognises that the only two countries who lay claim to sovereignty are the United Kingdom and Argentina."



Argentine president Christina Kirchner upped the ante recently over the Falklands.



She wrote an open letter earlier this month to David Cameron accusing Britain of stripping the Falklands from Argentina in an aggressive act of colonialism 180 years ago.



The Sun newspaper wrote a reply to Mrs Kirchner, published in Argentine newspapers, pointing out British sovereignty over the Falklands dates back to 1765.



The islanders are due to vote on sovereignty in a referendum on March 10 and 11.



They are expected to send a firm message to Argentina they wanted to remain British.



