The government has struck a deal with Telstra and Optus to gradually take control of their copper and pay TV wires to expedite the rollout of the national broadband network (NBN).

NBN Co renegotiated its agreement with the telcos to include the acquisitions of the copper and hybrid fibre coaxial (HFC) networks at no incremental cost to the taxpayer.

The value of the deal it originally struck with Telstra remains the same, $11bn, despite the takeover of the ageing wire networks.

The communications minister, Malcolm Turnbull, praised the agreement as a “great step forward” that gives NBN Co a chance to decide what technology works best for the rollout of the broadband scheme.

“The mix of technologies that the NBN will use are the leading cutting-edge technologies and techniques being used by the leading telcos around the world,” Turnbull told reporters on Sunday. “They will ensure that all Australians have access to very fast broadband, much sooner and at much less cost and much more affordably.

“This should be seen as a win-win: a win for the taxpayer, a win for the consumers, a win for National Broadband Network and for Telstra shareholders ... and the project will be completed much sooner and at much less cost.”

The head of NBN Co, Bill Morrow, said keeping the old networks would be less invasive than installing fibre cables.

“The majority of homes across the country will no longer need to have their gardens dug up, their driveways broken apart or equipment mounted on their homes,” Morrow said.

“The way the agreement works is that we have a right to go with whatever assets exist today and we intend to use all of that. Where the copper exists today and we intend to use it, it’s our choice, our prerogative, of how much we intend to use. For example, if the copper is unsuitable for us to be able to get the data speeds we are expecting, we don’t have to necessarily take over that responsibility,” Morrow said.

While the acquisition of the copper and HFC networks will be absorbed into the cost of the existing government agreements with the telcos, taxpayers will have to pay for operating and maintaining the ageing cables.

“Under the revised agreements … we will progressively transfer the ownership and the operational maintenance responsibilities for the relevant copper and HFC assets to NBN Co,” said David Thodey, chief executive of Telstra.

Labor said the government had “sold out Australia” by buying technology that a previous Liberal prime minister, John Howard, had sold.

The Labor spokesman for communications, Jason Clare, said: “Don’t believe the idea that this is free. This is going to cost taxpayers billions and billions of dollars to maintain and upgrade this old copper network. This is a copper nail in the coffin of the NBN. This is not the NBN that most Australians want.

“The reality is that the Australian taxpayer has just assumed all the risk associated with these two assets – the copper network and the HFC network,” Labor’s Michelle Rowland said. “You get a slower, second-rate network.”

NBN Co aims to give all homes and businesses high-speed broadband by 2020. There are 8m premises connected to the NBN.