On May 5, .1983, Vanuatu issued a souvenir sheet depicting its own economic zone (Zone économique). The two islands Umaenupne (Matthew Island) and Umaenenag (Hunter Island) were also included on the south-eastern edge of the island map of Vanuatu, which extended over three stamps. These were also shown enlarged on two of the six stamps. France made a submission to the Universal Postal Union (UPU) with the request to inform the UPU members related to the souvenir sheet. This was realized in Circular 148/1983 of the UPU with the corresponding content. It pointed out that the two islands (Matthew and Hunter) were under French sovereignty and that the souvenir sheet would give the false impression that they would belong to Vanuatu.