US loses last perfect credit rating amid rising debt

The US has lost its last perfect credit rating, as influential ratings firm Moody's expressed concern over the government's ability to pay back its debt.

In lowering the US rating from 'AAA' to 'Aa1', Moody's noted that successive US administrations had failed to reverse ballooning deficits and interest costs.

A triple-A rating signifies a country's highest possible credit reliability, and indicates it is considered to be in very good financial health with a strong capacity to repay its debts.