Activists staged a protest against cuts in public services at a Surrey bank as part of a national day of action.
Members of Redhill Coalition Against Cuts, dressed in white coats and gowns, set up a pretend hospital in NatWest, Redhill, at about 1030 GMT on Saturday.
They said they continued their protest outside when police asked them to leave about 40 minutes later.
A spokeswoman for RBS, which owns NatWest, said: "We fully respect the right to peaceful protest."
She added: "Minimising disruption to our customers is our priority."
The protest was part of more than 40 demonstrations across the country, organised by the group UK Uncut.
Redhill Coalition Against Cuts said it targeted NatWest because its parent company RBS received billions of pounds from taxpayers during the financial crisis.
Sarah Finch, of Redhill Coalition Against Cuts, said: "People are appalled at the size of bankers' bonuses and want banks to pay their way.
"If banks paid their fair share we could avoid the worst of the cuts and job losses threatened for Surrey and elsewhere.
"It's time to remind the banks that they serve everyone not just the super-rich."