Police outside a school in England. Photo: Terry Harris

More than 400 schools across England were caught in a series of bomb threats on Monday morning.

According to The Guardian, Humberside police said more than 400 schools and colleges across the country, including 19 in its region, had received emails ?claiming a device has been planted and demanding cash?. Following this, dozens of schools were evacuated as a precaution.

The emails believed to have come from the United States were sent to schools across the UK. Schools in London, Yorkshire, Humberside and Northumbria were all sent the threat and there were similar reports in Suffolk and Essex.

Northumbria Police confirmed more than 35 schools in its region received emails threatening to detonate explosives on their grounds if cash was not handed over.

?Schools have been visited by police to reassure them that the incident is being treated as hoax and address any concerns,? Northumbria Police said in a statement.

"The emails inform the school that a bomb has been placed on the grounds and will be detonated if they don't hand over cash. Detectives have looked into the emails, which appear to originate from the US, and can confirm there is no viable threat,? the statement added.

Police officers visited the schools to reassure pupils and staff.

The Metropolitan Police issued a statement saying, "Police are investigating reports of communications made to a number of schools across London today, Monday, 19 March. There have been no arrests. Enquiries are ongoing.".