This assessment has been partly attributed to the challenging economic environment created by Brexit.

A Fitch Rating spokesperson said: “Our UK GDP growth forecasts are materially weaker than before the Brexit vote.

“Uncertainty about the path of Brexit and the progress of negotiations will weigh on the economy.

“Higher unemployment and inflation, uncertainty around real estate prices and reduced credit demand would put pressure on asset quality and profitability at a time when profits have been muted for several years.

“Profitability has been hurt by low growth and low rates, and conduct and litigation costs.

“Most of these pressures are likely to persist.

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“We believe cost control will, therefore, remain a high priority for 2017 as UK banks cope with these economic pressures and structural changes.”

Fitch considers the rated UK banks' capitalisation generally commensurate with their risk profile.

In its assessment, Fitch has taken into consideration its expectation that there will be large conduct fines and penalties for some banks.

It added: “The UK banking sector is undergoing major structural reforms, which will add to costs until at least 2018.

“Larger banks are preparing to meet ring-fencing requirements by the start of 2019.

“UK banks are likely to disclose near final ring-fencing plans in 2017.”