Residents opposing plans to build a 33m radio mast near a park are stepping up their campaign after the council said it was powerless to prevent it.

Network Rail (NR) wants to build the mast on its own land on the Norwood Park borders, claiming it is “essential to replace an out-of-date system and critical in stopping rail crashes”.

But residents in Gipsy Road and Finch Avenue said the mast was too tall and would affest their houses and a protected view of the park. They claimed other sites would be more suitable.

Councillor Steve Reed, Lambeth Council leader, said: “We back residents all the way and oppose NR putting this mast up and ruining a protected view that residents cherish very much.

“Although, frustratingly, we have no powers to prevent NR we will do everything we can to use our influence to get it to see sense and drop these plans, and to lobby Government to give councils the necessary powers to stop this kind of thing in future.”

Construction was due to be finished by the end of January but has been halted after protests by residents.

Dulwich and West Norwood MP Tessa Jowell has taken up their cause and written a letter to Nick Gray, head of customer relations at NR.

An NR spokesman said: “In the case of the Norwood Park mast, we were limited to a short stretch of track at the top end of the park.

“Within the available area, we chose the location where there were most trees to try and visually screen the mast from as many people as possible.”