Asked about amateur investigators breaking into properties near where Ms Bulley was last seen along the River Wyre on 27 January, Superintendent Sally Riley told a press conference that there are empty or derelict properties along the riverside and entering them without permission would be a criminal act.
She said: “There are some properties along the riverside which are empty or derelict and whilst it may be well-intentioned that people think that that could be a line of inquiry, I would ask them to desist from doing that.
“In some cases it may be criminal if they are breaking in, causing damage or committing a burglary”.
Police investigating the disappearance of Ms Bulley have urged the public to avoid “distressing” speculation about what may have happened to her and warned that it was distracting for the police inquiry.
Superintendent Sally Riley said: “We would ask that people in the wider community, particularly on social media and online, do not speculate as to what may have happened to Nicola.
“This is particularly hurtful to her family, to her children, to her partner Paul, to her parents, her sister and her friends because it is not helpful to them, it is distressing and it is distracting for the police inquiry.
“Nor is it helpful if people, particularly if they have come from outside of the area, take it upon themselves to take the law into their own hands by trying to, for example, break into empty property,” Supt Riley continued.
“They may mean well, they may want to help. But they can help in thinking back if they were in the area to what information they may have of relevance to the police and holding the family in their thoughts.
“But we will not tolerate online abuse of anyone, including innocent witnesses, members of the family and friends, of local businesses, or of criminal damage or burglary. We will be taking a strong line on that, as you would expect.”
Lancashire Police said they were open to receiving any credible information but it remained their belief that Ms Bulley had fallen into the river.
The force has been working with the Coastguard, Lancashire Fire and Rescue and underwater search experts Specialist Group International (SGI) to search the river and riverbank using sonar, pole cameras and underwater drones, but the 45-year-old’s body has not been recovered.
Supt Riley added: “As I said on Friday, the river is a complex area to search, it’s not a still water, it’s a fast-flowing moving water that is tidal in parts, and as acknowledged by some of the many national search advisers and experts ... this makes it particularly complex.
“We have already discounted particular areas of the river but as they are tidal we have re-searched them to ensure that nothing has been washed back into those searched areas.”
Ms Bulley vanished without a trace along the River Wyre after dropping her two daughters, aged six and nine, off at school.
Her family dispute the police’s theory that she has gone into the river and have asked private underwater search team to search the river for her.