Dissident republicans claimed they left a bomb near Londonderry, police said.
Major disruption has been caused in Lettershandoney, with families displaced from their homes.
PSNI superintendent Gordon McCalmont said those behind the incident should provide clear and accurate information.
"Over a period of two days violent dissident republicans have been telling us through intermediaries that there is a bomb in the area of Lettershandoney.
"On Wednesday they told us it was in one position and yesterday they said it was in another. They are providing conflicting and inaccurate information and creating fear and concern within the local community."
He said families were forced from their homes at a time when they should be managing the routine of getting children back to school.
"The criminal elements behind this incident don't care about family life or the added stress they are placing on people forced to leave their homes.
"Keeping the community safe is our priority and while this is a challenging security operation we are grateful for the patience those affected have shown.
"I am calling on those behind this incident to tell us exactly where the bomb is so we can deal with it alongside our specialist colleagues or, indeed, clarify if there is no bomb.
"Meanwhile the policing operation will continue so that we can ensure the area is safe and allow families to return to their homes."
Police are on high alert for more attacks by dissident republicans.