Oil prices jumped above $100 a barrel as energy markets reopened on Monday in Asia after talks between the US and Iran ended without a new deal and Donald Trump said he would blockade Iranian ports.

Global benchmark Brent crude is up by 8.5% at $102.37 (£77.15), while West Texas Intermediate is 9% higher at $105.34.

The failure of negotiations at the weekend has raised concerns that the global energy crisis will deepen.

The price of oil plunged well below $100 last Wednesday after Washington and Tehran agreed to a conditional two-week ceasefire deal that includes the opening of the key Strait of Hormuz trade waterway.

The conflict is now a test of wills - Iran’s capacity to absorb strikes versus Trump’s tolerance for the war's costs.

It was a difficult mission, negotiating on behalf of a president whose messaging on the war has been mixed from the start.

Trucking operators say their costs have doubled in a vast country reliant on the industry to deliver goods.

Taoiseach (Irish PM) Micheál Martin said groups "with a self-declared" mandate have imposed blockades.

Twenty-one hours was not enough to end 47 years of hostility between Iran and the US, writes the BBC's Lyse Doucet.