The Queen is to head a 1,000-strong flotilla of boats during a spectacular River Thames celebration marking her 60-year reign.

The Diamond Jubilee River Pageant will be one of the highlights of a special four-day bank holiday weekend next June created so the nation can mark the monarch’s milestone.

The extravaganza, expected to be the largest flotilla created in decades, is the first major public event marking the jubilee to be announced.

The Queen will be on a vessel at the head of a fleet made up of boats from the UK, Commonwealth countries and the wider world.

More than a million people are expected to flock to the banks of the Thames to witness the celebrations on Sunday, June 3 next year which will integrate music, daytime fireworks and special effects.

London Mayor Boris Johnson said: “I cannot conceive of a more fitting celebration of Her Majesty’s 60 years on the throne than a majestic flotilla of vessels, large and small, winding their way along the iconic River Thames and showcasing our proud maritime history.

“This magnificent pageant will not only provide a terrific focal point for Diamond Jubilee commemorations, but will demonstrate to the world London’s pride in its heritage and traditions.”

The Queen will reach her milestone on February 6, 2012 - the 60th anniversary of her accession to the throne.

The flotilla of up to 1,000 vessels is expected to be seven-and-a-half miles long and will feature a mix of historic and modern boats in both private and commercial hands.

Everything from rowing boats and sailing ships to steamers, wooden launches and larger motorised craft will be represented and the public are invited to take part with their own vessels.

The flotilla will be made up of five sections each separated by a “herald barge”, the first of which will be a floating belfry of eight new bells cast by the Whitechapel Bell foundry in east London and commissioned by the 17th century City Church of St James Garlickhythe.

Their peals will be answered and echoed by chimes from riverbank churches along the route.

Other barges will feature water jets and sprays, reminiscent of the old Thames firefighting boats, live entertainment and music from the six decades of the Queen’s reign, and a pyrotechnic barge which will entertain the crowds with daytime fireworks and a mechanical flame-spitting dragon.

The water-borne parade will include representatives from the Armed Forces and the emergency services and passenger boats carrying up to 30,000 people.

The government designated June 5, 2012 as a bank holiday for the Queen’s Diamond Jubilee and, to enable a four-day weekend of celebrations, the late May bank holiday has been moved to Monday, June 4.

The pageant is being organised by the Thames Diamond Jubilee Foundation chaired by Lord Salisbury and funded by private donations and sponsorships.

Lord Salisbury said: “We are planning the greatest Thames flotilla for 350 years to mark Her Majesty’s Diamond Jubilee.

“I believe that we should recognise her 60 years of selfless public service with an event that can properly express our admiration and gratitude. The pageant is just that.”