Artist Emin is famous for displaying her unmade bed

The controversial artist, 43, wrote "One Secret is to Save Everything" on the banner in red capital letters.

The flag, the second in a series of Southbank Centre commissions, will be displayed in London until 31 July.

Hayward Gallery director Ralph Rugoff praised her "precise sense of paradox and ambiguity in subverting what might be a reassuring formula for happiness".

"We are delighted that Tracey has designed such a thought-provoking flag for Southbank Centre," he added.

Emin called the artwork "a flag made from wishful thinking". It has been erected on a 100ft-tall flagpole in London's Jubilee Gardens.

It is not the first time the artist, best known for her unmade bed, has featured flags in her work. Her 1999 Turner Prize show included No Chance (1999), a fabric image of the Union flag alongside stitched protest statements.