BT has unveiled a £6billion programme to upgrade its network in a move to extend ultrafast broadband to at least 10million homes and businesses, and lay fibre optic lines to around two million premises across the UK.

The telecoms giant also pledged to improve its customer service under the investment plan, as it seeks to appease regulator Ofcom which has threatened to force a split of its Openreach fixed-line network arm.

Details of the invedstment plan came as BT announced a 15% rise in pre-tax profits to £3.03bn for the year to March 31 after seeing revenues rise by 6% to £18.9bn.

Part of the three-year initiative will see BT focus on replacing its ageing copper wire that most homes rely on for internet access, with aims to roll out fibre optics to two million homes and businesses – mainly in new housing developments, high streets and business parks.

Ofcom recently stopped short of ordering a split of Openreach, but told BT it must cut prices charged for high-speed lines, install more business lines and improve business services.

BT said the £6bn investment marked the first phase of a plan to extend ultrafast broadband to a minimum of 10m premises, with aims for it to reach 12m by 2020.

It also announced a raft of customer service improvements to reduce the standard time to fix line faults by 24 hours as well as pledging to handle 90% of customer calls in the UK by March next year.

The group added that Openreach will hire another 1,000 engineers this year to help improve its service.

Gavin Patterson, group chief executive at BT, acknowledged that the group needed to “work hard” to meet increasing customer expectations, adding: “That is why contact centre work is being returned to the UK and why Openreach is aiming to halve the number of missed appointments within a year.

“Customers want higher standards of service and we are determined to provide them with just that.”

Ofcom told BT earlier this year that it must open up its Openreach network to competitors in its first significant review of the telecoms sector for a decade.

It is also enforcing tougher rules on faults, repairs and installations for consumers, clearer information on service quality, and automatic compensation for disruption.