Fitch announced on Thursday that it has lowered its ratings for British state-rescued lenders Royal Bank of Scotland and Lloyds, citing the reduced likelihood of further government support.
The move "reflects Fitch's view that support dynamics are changing in the UK," Fitch said in the statement.
Fitch said it had lowered its support rating floors (SRF) for systemically important UK banks to 'A' from 'AA-' and 'A+'.
As a result, the agency cut the long-term issuer default ratings for both Lloyds Banking Group (LBG) and Royal Bank of Scotland (RBS) to 'A' from 'AA-'. Fitch has also placed Barclays on ratings watch negative.
"The banking system is not only large relative to the UK economy, but there is also more advanced political will to reduce the implicit support for the country's banks," Fitch said.
It continued: "The lower SRF indicates that the potential for the provision of extraordinary support for senior bank creditors is relatively less certain than before."
The announcements came one week after Moody's downgraded its ratings for a dozen British lenders, including RBS and LBG, and cited the "significantly reduced" chances of further support over the medium- to long-term.