Officers are currently on the scene of an incident in Stacey Bushes.
UPDATE 17:05PM - A Thames Valley Police spokesperson has given the following update:
“Emergency services have now left Myrtle Bank, Stacey Bushes. The substance has been safely removed and the road has reopened.
“Thank you to the local community for your patience whilst we dealt with this.
“An investigation will now be carried out.”
15:32PM - A spokesperson for Thames Valley Police said: "Officers are currently in Myrtle Bank, Stacey Bushes following a report of a suspicious substance being delivered to a property.
"The fire and rescue service and ambulance service are also on scene, whilst work is ongoing to ascertain what the substance is.
"There isn’t believed to be a wider risk to the public, however the road is currently closed at both ends as a precautionary measure and local residents are advised to keep their windows and doors closed at this time until the substance has been identified.
"We will issue an update when we can."
