The United Kingdom has announced it entered into an agreement to hand over the Chagos Islands to Mauritius, a development that is set to end decades of disputes and negotiation over Britain’s last African colony.

The agreement follows 13 rounds of talks, which began in 2022.

Then, Mauritius, which called for sovereignty, was recognised by the International Court of Justice (ICJ) and the UN General Assembly in 2019 and 2021.

The World Court, as the ICJ is known, is the principal judicial organ of the UN, which adjudicates disputes between nations.

Before granting independence to Mauritius in 1968, Britain was found to have unlawfully separated it to form a new colony on the Chagos archipelago named the British Indian Ocean Territory (BIOT).

Also, the UK had initially dismissed UN rulings and court judgments demanding it return the islands to Mauritius, arguing that the ICJ ruling was merely an advisory opinion.

Before splitting the islands from Mauritius, the UK government expelled between 1,500 and 2,000 islanders.

The action leased Diego Garcia, the largest of the Chagos islands, to the U.S. for military use, which the two allies have since operated jointly.

Reports had said the UK falsely declared that Chagos had no permanent population so that it would not have to report its colonial rule to the UN. In reality, the Chagossian community had lived on Chagos for centuries.

The UK and U.S. governments forcibly displaced the Chagossian population between 1967 and 1973, not only reportedly on Diego Garcia but also on Peros Banhos and Salomon.

The campaign challenging British ownership of the Chagos archipelago included the Mauritian ambassador to the UN, Jagdish Koonjul, raising his country’s flag above the atoll of Peros Banhos in a ceremony in February 2022.

The ceremony marks the first time Mauritius had led an expedition to the territory since the expulsions.

Following the new agreement, the UK will retain control of the UK-U.S. military base on Diego Garcia.

David Lammy, UK Foreign Secretary, said the UK government had secured the future of the military base “as well as guaranteeing our long-term relationship with Mauritius, a close Commonwealth partner.”

However, many Chagossians are still frustrated by the UK government’s lack of consultation with them before the announcement.