The high class dish will contain Japanese Kobe beef, and instead of ketchup will be garnished with foie gras and rare blue cheese, the Daily Star tabloid said.
Kobe beef, also known as the 'caviar of beef', comes from Japanese cows tenderly raised on a special diet of beer and sake, ensuring the meat is the most tender and succulent in the world.
Extras could include truffles instead of mushrooms, as well as tiger prawns and guacamole.
The burger, which has beaten the previous record of 80 British pounds for the most expensive sandwich sold two years ago in a New York restaurant, will be available at selected branches in Kensington and Chelsea in southwest London from May.
The company, which offers a budget cheeseburger for just $1, explains that the move is likely to position itself away from rival McDonald's and other fast food chains.
A spokesman for Burger King told the newspaper: "We can confirm that we're currently developing what will be potentially the UK's most expensive burger."
"It is a reflection of our ongoing commitment to serving up the best quality ingredients for a range of different pockets."
