Police are investigating after two telegraph poles installed as part of a controversial broadband project were cut down.
The poles, erected by MS3 Networks in the Longhill area of Hull, were felled over the weekend.
It prompted the company to issue a warning about the dangers of criminal damage.
A Humberside Police spokesperson said: "We are investigating reports of criminal damage caused to telegraph poles on Waveney Road in Hull at around 8pm on Friday, 17 September."Officers are carrying out lines of enquiry, including reviewing CCTV footage in the area around the time of the incident to identify those involved."
MS3 has been installing poles on residential streets in parts of East Yorkshire in recent weeks, prompting complaints that they are an eyesore.
Police have been involved in keeping the peace during protests in parts of Hedon and Hessle, as some residents attempted to physically block the installation of poles close to their homes.
But campaigners have called on people not to take matters into their own hands.
Protester Julie Annette posted on Facebook: "Please note that whilst we do not advocate any criminal actions, this group entirely understands the strength of feeling that leads to this sort of occurrence.
"Unfortunately, chopping down these poles will not impact on the companies who install them."
The mayor of Hedon, Cllr Steve Gallant, wrote: "We must not support or condone any criminal damage to the posts installed. Not only is it criminal damage, it is also dangerous to the individual and any cars or property in the vicinity."
In a statement MS3 said: "Telegraph poles weigh hundreds of kilograms and there is very real danger of loss of life from deliberately damaging them.
"Whilst the police investigation is under way we cannot comment on the act itself however we are extremely disappointed with the actions of members of local protest groups condoning this behaviour online."
The firm said "harassment" faced by its staff when they installed the poles and "misinformation posted online" had led to "a small group of individuals deciding to commit a serious offence that may have endangered lives".
Campaigners want the company to use existing underground infrastructure managed by telecommunications company KCOM.
KCOM has provided telephone and broadband connections in Hull and the surrounding area almost exclusively for almost 120 years.
Under Ofcom rules, it must provide other operators access to its network. But MS3 says its charges are prohibitive.
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