BT has announced plans to trial one gigabit fibre broadband in Suffolk and add 40 rural market towns to its current fibre roll-out.
It said the move would support the UK government's plan to create the best broadband network in Europe by 2015.
It comes as regulator Ofcom reveals that less than 1% of UK homes have a super-fast broadband connection.
Culture Secretary Jeremy Hunt is due to spell out the UK's broadband strategy next week.
The 1Gb trial in Kesgrave, Suffolk, will begin early next year and is intended to demonstrate the speed capabilities of BT's fibre-to-the-home (FTTH) technology.
BT has been criticised for not offering FTTH more widely. Most of its fibre roll-out will rely on slower fibre-to-the-cabinet (FTTC) technology.
Only a quarter of the homes it intends to offer fibre to will be connected using FTTH.
The market towns earmarked for broadband upgrades have not yet be named but BT said it intended to begin offering services from late 2011.
The announcement comes ahead of a speech on the issue from Culture Secretary Jeremy Hunt.
"I will be setting out on Monday how we can do even more to boost broadband roll-out - by stimulating competition and creating an environment in which business can flourish by removing barriers and cutting costs," he said in a statement.
The government is set to provide £830m for firms willing to offer fast broadband services in rural areas, which it will provide "over the course of this parliament and the next".
BT said that if it was to "win funds on that scale" it would be able to provide fibre to 90% of the UK.
Under current plans, its fibre will extend to 66% of the UK.
"We intend to continually push the limits of our super-fast broadband programme in terms of the technology and the geography," said Oliva Garfield, BT's director of strategy.