The situation has become so serious that the government is considering employing security staff to protect firms who remove the antennas.
An investigation by Building has found that some workers have been assaulted and had the windows of their vehicles broken.
At other times members of the gangs have attempted to deter staff by taking down the number plates of vans they are using. At other times the gangs have attempted to intimidate workers by following them.
A DTI spokesperson said: "We have heard of threats and attacks on council and contract maintenance workers and our advice is to be on guard, not to risk safety, and to call us or the police if there is suspected pirate activity."
A government insider said that radio pirate gangs had strong links with organised crime and the drugs underworld.
Pirate radio advertises meeting points for drug deals – so the stakes are very high
He said that they used the illegal transmissions to advertise unlicensed dance events with the intention of selling drugs at them.
He said: "That is why it is difficult to act against these pirate radio stations. They are a window to the drugs underworld and they need to be in operation to advertise meeting points for drugs deals – so the stakes are very high."
A DTI insider said that the government and local authorities were considering installing rooftop security guards as a short-term solution to the problem.
He said: "At the moment it is only an idea, but there are talks with local authorities about having security on the rooftops at key times when the pirates want to broadcast, like at the weekend."
The gangs make transmissions from the tops of tower blocks in areas such as Hackney, north London, for two reasons: firstly, because the reception is good and, secondly, because normally there is little chance of interference.
The DTI launched a clampdown on pirate radio broadcasters last year when the Radio Communications' Agency, an executive agency of the DTI, carried out 1046 anti-pirate radio enforcement operations throughout the country. This led to 39 prosecutions.