Britain’s credit rating was at risk of a downgrade if it failed to preserve core elements of its access to the European Union’s single market, ratings agency Moody’s said yesterday.

“The UK’s Aa1 sovereign rating would be downgraded if the UK’s loss of access to the European Single Market following Brexit were to materially weaken medium-term growth and if the credibility of UK fiscal policy were to be undermined,” Moody’s said in a statement.

Moody’s assigned a negative outlook to Britain’s credit rating the day after the country voted to leave the EU, saying it expected heightened uncertainty and weaker confidence to slow growth.

Yesterday, Moody’s said the scale of the impact of Brexit on its growth prospects would depend on Britain’s new trading relationship with the EU.

“One scenario that Moody’s considers to be realistic is a series of accords offering access to the EU market for goods and more constrained access for services, in particular financial services. However, such an outcome is far from certain,” it said.