It has identified an extra £200 million to be taken off bills for households off the gas grid, who it found to be missing out on energy deals offered to other consumers.
Ofgem chief executive Alistair Buchanan said it was "encouraging" that moves have been announced by energy firms since the end of the initial investigation.
"We've seen progress but it's certainly not the endgame," he added.
"And we are about to consult on new rules to end unfair pricing in the future".
In response to the announcement by Ofgem, Phil Bentley, managing director of British Gas said his firm was "fully confident" that it will meet all requirements for "transparency and fairness".
He added: "We are pleased Ofgem has recognised the efforts that have already been made to reduce the difference between the costs of pre-payment meters and standard tariffs."
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