Investors have recently been unnerved by a string of bank failures.
But US stock markets were higher after Treasury Secretary Janet Yellen signalled the US government would protect people's deposits if another bank collapsed.
In the UK, the FTSE closed 1.79% higher after gains in top bank shares.
NatWest, Prudential and Barclays shares gained about 5%, while Standard Chartered and Lloyds also traded higher.
Ms Yellen said "the situation is stabilising, and the US banking system remains sound" in a speech on Tuesday.
This follows the collapse of Silicon Valley Bank and Signature Bank earlier this month.
The failures were triggered by depositors rushing to withdraw money after anxiety over the banks' health.
And last week, a group of the biggest US banks raised $30bn (£24.5bn) in funds for regional lender First Republic Bank, but its share price still crashed by more than 45% on Monday.
Ms Yellen said the US intervention in the two bank collapses was necessary to "protect the broader banking system", after promising that all depositors in both banks would be protected.
She added that similar action could be taken if if the same happens to other smaller banks, indicating that savers would not lose their money if another bank were to collapse.
Meanwhile, in the UK Chancellor Jeremy Hunt told MPs that the UK's financial system is "fundamentally strong" after facing questions from Labour's shadow chancellor Rachel Reeves.
Ms Reeves asked whether the system is "adequate to protect taxpayers and depositors" and if the government can be confident that no other UK banks are vulnerable to failure after Silicon Valley Bank UK's collapse.
There has also been further instability, including Swiss bank Credit Suisse having to be rescued by rival UBS.
Mr Hunt said that markets are unsettled, but the UK financial system is "fundamentally strong" and UK banks are have enough money - much more than before the 2008 financial crisis.
"We continue to monitor the situation carefully," he added.
The Bank of England along with six central banks around the world, including the US Federal Reserve, joined forces on Monday to help contain the spread of the crisis by boosting dollar flows into the financial system.
It means that banks can borrow dollars from the central bank through the course of the seven-day-a-week facility.
But so far, no banks have used the so-called swap line, suggesting that stress levels in the UK banking system are currently low.