Fitch Ratings on Friday downgraded Britain's debt a notch and lowered the outlook to negative, citing the "significant weakening" of public finances and damage to the economy from the coronavirus pandemic.
"The coronavirus outbreak has inflicted an unprecedented shock on financial markets and economic activity, with policymakers struggling to avert a longer-lasting downturn," Fitch said in a statement.
In addition, lingering uncertainty over Brexit and the "uncertainty around the future trade relationship with the EU could constrain the strength of the post-crisis economic recovery.