Energy Secretary Grant Shapps will meet bosses from Asda, Tesco, Morrisons, Sainsbury's and other major fuel retailers on Monday, who will be "held to account for any failure to pass on savings to consumers".
Announcing the scheme earlier in July, Mr Shapps said the government wanted to "shine a light on rip-off retailers".
The secretary of state will give retailers until next month to agree to the voluntary Competition and Markets Authority (CMA) scheme to share live fuel prices, in order to improve transparency and increase competition.
"Act now or face the full force to the law," the Department for Energy Security said. A failure to comply would see retailers legally forced to share their prices, it added.
Petrol and diesel prices jumped to record highs following Russia's invasion of Ukraine last year, but have since dropped significantly.
However, the CMA, the UK's competition watchdog, investigated the UK fuel market earlier this year following concerns falling wholesale prices were not being passed on to consumers.