The United States Senate has begun hearings into whether a referendum should be called to decide the political status of Puerto Rico.

In March the House of Representatives approved a bill offering Puerto Ricans a referendum to decide if they wanted to remain a self-governing protectorate, to become America's fifty-first state, or become fully independent.

The latest debate begins as Puerto Rico prepares to mark the one-hundredth anniversary of its transfer from Spanish to US sovereignty in ten days time.

In a non-binding referendum five years ago, Puerto Ricans voted by a narrow majority to remain a US protectorate.

The current status means Puerto Ricans can serve in the US military, but have no voting rights in US presidential or Congressional elections.