Image copyright Getty Images Image caption The Queen celebrates two birthdays - her actual birthday in April and her official birthday in June

Tickets for a street party to mark the Queen's 90th birthday in The Mall will cost £150, her grandson has announced.

Peter Phillips said the Patron's Lunch on 12 June was a not-for-profit event and would have a "carnival atmosphere".

Most of the 10,000 guests will be from organisations of which the Queen is patron, with 1,000 tickets to be released in a public ballot next month.

Mr Phillips said the event was "not exactly a cheap exercise" but any surplus would go into a charity fund.

The majority of tickets for the event will be made available to the more than 600 charities and organisations associated with the Queen, which include Cancer Research UK, the British Red Cross and Barnardo's.

They will be asked to pay £125 plus VAT - a total of £150 - per ticket, but will be allowed to raise money with 40% of their tickets.

In February a ballot will open to the public for a minimum of 1,000 tickets, with winners able to buy them from the event's website.

'Genuine value'

Each guest will receive an individual hamper of food at tables set up along the length of The Mall, where entertainers will perform.

The cost of the event is being subsidised by corporate sponsors and official partners, including Boots, BT, Pimms, M&S and Unilever.

It is being organised for an undisclosed "set fee" by events company Sports and Entertainment Ltd (SEL), of which Mr Phillips is a director.

Remarking on the cost of the tickets, Mr Phillips said the event's corporate partners had "provided the funding for the majority of the costs".

He said: "This is a not-for-profit event. SEL is being paid a set fee basically to take this from sign-off from the palace through to delivery of the event."

A spokeswoman for the Patron's Lunch said support from the event's partners did not cover its costs fully and tickets offered "genuine value".

Some charities welcomed the event as a way to celebrate the Queen as their patron, and raise awareness.

Action for Children said The Patrons' Lunch was a "unique opportunity to be able to reward some of our volunteers and supporters".

The Dogs Trust said it was an opportunity to "raise vital awareness and funds for our key campaigns with supporters and influencers".

However, international Christian charity Mothers' Union, whose first royal patron was Queen Victoria, said it understood why questions had been raised about the cost of tickets, and was still considering whether to participate.

"We look towards the event as a potential opportunity, one which must ultimately support our work and beneficiaries if there is to be any cost at all," head of fundraising and communications Daniel McAllister said.

Image copyright Patron's Lunch Image caption The street party at The Mall will take place in June

The party, which Princes William and Harry will also attend, will be the culmination of a weekend of national celebrations.

The Queen celebrates two birthdays each year: her actual birthday on 21 April and her official birthday on a Saturday in June - this year on 11 June.

The organisers hope communities around the country will be inspired to stage Patron's Lunches in their own areas and raise money for local projects.

Other events taking place over the Queen's official birthday weekend will include a service of thanksgiving at St Paul's Cathedral and the traditional Trooping the Colour ceremony, also known as the Queen's Birthday Parade, at Horse Guards Parade.

Any surplus money from the Patron's Lunch will be allocated to a newly created Patron's Fund, which will be used to support specific initiatives and projects run by the Queen's charities.

'Up to something'

Mr Phillips said the Queen had heard about his plans before he had a chance to tell her, and thought they were "a great idea".

He recalled that upon approaching her with the idea she said: "I've heard you're up to something."

He added: "There's a huge amount of pride, the fact that I'm able to celebrate, to put something on, to put a celebration on which ultimately she appreciates, she enjoys and she thinks is a great idea."