Staff at Barratt Homes offices across the UK have been sent death threats and letters containing suspicious white powder.

A police investigation is now under way to trace the source of the letters, which were received last Tuesday. One of the letters, delivered to offices on the Brackmills industrial estate in Northampton, said “death to all Barratt employees”.

The white powder enclosed with the letters was analysed and found to be harmless.

The letters were sent to offices in 10 areas, including Kent, Aberdeenshire and Northumbria.

A spokesperson for Nottinghamshire police, which is leading the investigation, said: “We are not disclosing any further information about the powder or its components but we can confirm that it is totally harmless.”

It is thought that the threatening mail is from an objector to a Barratt development on a brownfield site in the Midlands.

Police have ruled out any connection to recent terrorism alerts.

A spokesperson for Barratt Homes said:

“It is true that some of our offices have been targeted by a hoaxer sending threatening mail. The white powder was found to be harmless and we have nothing further to add at this point.”