The Treasury has been forced to intervene in an attempt to stabalise financial markets following the impact of Rachel Reeves's Budget.
In the first statement since the mini-Budget in 2022, the Treasury dismissed suggestions that rising debt costs had wiped out Ms Reeves's headroom, saying it was "pure speculation" that she was in breach of her own fiscal rules.
The intervention came after the pound dropped as much as 1.2% against the dollar to $1.233, its lowest since April.
Meanwhile, UK 10-year borrowing costs surged to its highest level since the global financial crisis in 2008, jumping about 0.1 percentage points to 4.81%.
A Treasury spokesman said: “No one should be under any doubt that meeting the fiscal rules is non-negotiable and the Government will have an iron grip on the public finances.
“UK debt is the second lowest in the G7 and only the [Office for Budget Responsibility’s] forecast can accurately predict how much headroom the government has - anything else is pure speculation.
“Kick-starting economic growth is the number one mission of this Government as we deliver on our Plan for Change.
“Over the coming weeks and months, the Chancellor will leave no stone unturned in her determination to deliver economic growth and fight for working people.”
FTSE 100
The UK's flagship share index, the FTSE 100, was up five-points at 8,255 shortly after opening this morning.
Brent crude oil futures were up 0.15%, trading at $76.05 a barrel.