A legal row over ownership could result in the National Lottery being suspended for the first time in nearly three decades.
Camelot has run the game ever since it was launched in the early 1990s But the Gambling Commission in April confirmed plans to transfer the licence to rival operator Allwyn Entertainment.
The commission, which is responsible for regulating the betting industry, said in papers submitted to the High Court that Camelot has launched a legal challenge against the move.
