The health secretary said he expected its citizens to abide by a voluntary call for them not to leave for neighbouring places, because “they want to get their city back to normal”.
“We are not putting that in place in law at this stage,” he said, but he added: “Of course, we will if we have to.”
The warning came as Mr Hancock denied he had acted too slowly in imposing the fresh restrictions, acknowledging it was 11 days since he first was first alerted to a coronavirus spike.
He had been “monitoring it incredibly closely”, ramping up testing, including in workplaces with infections, and some schools in Leicester had already closed.
“These sorts of much more targeted measures have worked in other outbreaks,” Mr Hancock told BBC Breakfast.
“Unfortunately, that targeted action isn’t working in Leicester, that’s why we have taken the much broader measures. We have been on it.”