LONDON — Britain put its plan to transfer the Chagos Islands to Mauritius on hold after the administration of U.S. President Donald Trump withdrew its support for the handover deal. Legislation to ratify the agreement ran out of time in the current session of Parliament, which is scheduled to end within the next few weeks without the bill becoming law.

The deal is not expected to be included in the list of bills announced by King Charles III for the next session of Parliament beginning May 13. Under the agreement with Mauritius, Britain would lease back the Diego Garcia military base for at least 99 years.

The British government said in a statement: "Diego Garcia is a key strategic military asset for both the U.K. and the U.S. Ensuring its long-term operational security is and will continue to be our priority — it is the entire reason for the deal. We continue to believe the agreement is the best way to protect the long-term future of the base, but we have always said we would only proceed with the deal if it has U.S. support."

Prime Minister Keir Starmer's government has said the agreement would protect the Diego Garcia base from international legal challenge. The United Nations and its top court have urged Britain to return the Chagos Islands to Mauritius in recent years.

Simon McDonald, former head of Britain's Foreign Office, said: "When the president of the United States is openly hostile, the government has to rethink. This agreement, this treaty will go into the deep freeze for the time being."

The Conservative Party and Reform U.K. opposed the agreement on the grounds that transferring the islands would risk interference by China and Russia. Both parties had urged the Trump administration to rescind its support for the deal.

The Chagos Islands are a remote chain of more than 60 islands located off the southern tip of India, south of the Maldives. They have been under British control since 1814. The military base on Diego Garcia has supported U.S. military operations from Vietnam through Iraq and Afghanistan, and has served as a staging point for American bombers in the U.S.-Israeli war on Iran.

Islanders displaced from Diego Garcia in the 1960s and 1970s have said they were not consulted about the deal and worry it will make it harder to return home. Approximately 10,000 displaced Chagossians and their descendants now live primarily in Britain, Mauritius, and the Seychelles. Some displaced Chagossians have been unsuccessful in court challenges in the U.K. seeking the right to return home.