The first images of the long-awaited extension to the Tate Modern art gallery in London have been released ahead of its official public opening on 17 June 2016.

The Tate Modern was created in 2000 by Herzog and de Meuron, who transformed the derelict Bankside Power Station on the River Thames into a home for the UK’s collection of international modern and contemporary art.

The architects reunited eight years ago with original collaborators Vogt Landscape Architects and designer Jasper Morrison to create the extension on the site of the power station’s former Switch House.

The result, shown in the newly-released photographs by Iwan Baan, is a towering 10-storey pyramid – 65m (213ft) tall and 21,500sq m (230,400sq ft) in size – that has added 60 per cent more space in which to exhibit the Tate’s mammoth art collection.

Opening exhibitions at the new-look Tate will include work from 300 international artists, including Mark Rothko, Henri Matisse and Ai Weiwei – who will install a huge sculpture of a tree almost 7m (23ft) tall.

Architecturally, the Switch House is formed of a concrete structure that folds into dramatic lines as it rises. The power station’s brickwork is reinterpreted with a new perforated lattice of 336,000 bricks that allows light to filter in during the day and to glow out in the evening.

Inside, cylindrical underground tanks each measuring over 30m (98.5ft) across form the physical foundation of the building and provide space dedicated to live art, installation and film.

Above them are three additional floors of galleries ranging in size, scale and height to offer curators the maximum degree of flexibility. The other new floors include learning spaces, a restaurant, a bar and a public terrace with 360-degree panoramic views of the city.

A new bridge across the original building’s Turbine Hall connects the old and new sections of the museum.

The Switch House has cost a reported £260m (US$377m, €336m), almost £50m (US$72.5m, 64.6m) more than expected due to rising building costs. The Tate Modern currently receives 5m annual visitors, and this is expected to rise in the years ahead.

The extension has been described by the museum’s directors as “Britain’s most important new cultural building for almost 20 years”. It featured on CLAD’s New Year list of the most exciting new leisure buildings to look out for in 2016.