Views of some of London's most historic buildings could be threatened by new planning guidelines, it is claimed.
Views of St Paul's are protected
Westminster and City of London planners have raised concerns about the mayor's draft London View Management Framework.
Guidelines currently favour wide unobstructed views of buildings like St Paul's Cathedral and Parliament.
But a Westminster Council spokesman said views of key landmarks would be a lot narrower and skyscrapers could be built behind them, ruining the view.
"The general feeling is that this is an attempt by the mayor to change planning policies in such a way as to make it a lot easier to develop very, very tall buildings," he told the BBC News website.
"There are a lot of very tall buildings springing up and what we don't want is Westminster to be a low rise island surrounded by a forest of skyscrapers."
There are plans for several new skyscrapers - including the 1,016 ft (310m) Shard of Glass at London Bridge - said to be Europe's tallest tower block.
But current rules mean skyscrapers are limited to certain areas where they will not obstruct views.
Peter Rees, the City planning officer, said mayor Ken Livingstone wanted to narrow long-distance views of St Paul's from places like Hampstead Heath, Parliament Hill fields and Blackheath park.
"It would be a bit like seeing it through a gap in a fence," he said.
"Those views would all be reduced to the point where they really aren't worth having."
But the mayor's office said its plans would be modified after public consultation.
Alex Bax, Mr Livingstone's planning adviser, told the Daily Telegraph: "It should be possible to build high buildings where they do not get in the way of the view."