Tate director Sir Nicholas Serota has joined a protest against plans for a tower block which he says will overshadow one of the UK's most famous galleries.
Sir Nicholas Serota: " It will diminish quality and value of the space"
Councillors have given the go-ahead for a 20-storey tower block 50 metres away from Tate Modern's main entrance.
Sir Nicholas carried a placard saying "hands off our Tate" at the demonstration on Tuesday.
Planning consent for the block had originally denied by local authority Southwark Council, but it was granted in May after a public inquiry.
Objectors say such a tall building will affect the enjoyment of a visit to Tate Modern for millions of visitors.
Sir Nicholas said: "The public invested £135m in the creation of Tate Modern. A very tall building so close to its main entrance will inevitably diminish the quality and value of the space for millions of visitors.
"It is the equivalent of building a tower block in the forecourt of the
Tate Modern, housed in a former power plant, has been a huge success since opening three years ago, with millions visiting its exhibitions.
It has been credited with fuelling a renewed interest in modern art in the UK.