Alan Greenspan, the former president of the US Federal Reserve, has described Brexit as a "terrible outcome", claiming Britain should not have held a referendum to determine its destiny in the European Union.

David Cameron's decision to allow Britons to vote over the UK's future in the bloc was a "terrible mistake", which ultimately saw Britain poised to leave the union and cost the prime minister his job, throwing the country in political and financial turmoil.

Opting to hold a referendum led to a "terrible outcome in all respects," Greenspan said in an interview with Bloomberg, adding "It didn't have to happen."

The Leave campaign secured 52% of preferences at last week's historic vote, but the road ahead for the pro-Brexit movement looks far from straightforward, given the apparent lack of a concrete plan to steer Britain out of the EU.

The uncertainty surrounding Britain's future has seen the pound plunge to its lowest level in three decades, while the FTSE 100 lost 2.55% on Monday (27 June), extending Friday's losses as investors fled to safe havens.

Post-Brexit volatility is likely to continue but the former Fed president explained he had little sympathy for Britain's decision to leave the EU, insisting the soon-to-be 27-country bloc was in fact an excellent idea.

"The EU is fundamentally a very good idea," he said. "It's a free trade-zone structure, which we need an awful lot of, so that the choice of Britain to stay in the EU and yet out of the euro zone was, I thought, the most sensible action that could be taken."

However, Greenspan admitted the Eurozone remained a "truly vulnerable institution" and singled out Greece as the bloc's main issue.

"Get Greece out," he said. "They're a toxic liability sitting in the middle of a very important economic zone."