The Foreign Office said it does not recognise Mauritius' claim over the Chagos Islands after the latter planted its national flag on the Peros Banhos atoll on Monday.
The red, blue, yellow and green national flag was placed on the by Mauritian officials, who arrived by boat accompanied by Chagos islanders exiled more than 50 years ago.
Originally intended as a scientific survey, Mauritius' prime minister described the "historic visit" as "the first time Mauritius has led an expedition to this part of its territory".
