The Australian Greens say the rollout of fast broadband services can only be guaranteed if they hold the balance of power in the Senate.

The first stage of the National Broadband Network (NBN) will come online at Scottsdale, Smithton and Midway Point in Tasmania, later this month.

The Federal Opposition says the broadband plan is a reckless adventure, and says it will outline an alternative plan in coming weeks.

Greens Senator Christine Milne says Tasmania's future depends on fast broadband.

"We need new businesses, the future of those businesses depends on online marketing, online accessing sales, online education - we have to have it and we can't risk the Coaltion," she said.

Analysts say the NBN has widespread industry support.

Independent telecommunications analyst Paul Budde says the project, which promises to deliver high-speed television, video calls and chatrooms as well as educational and medical applications, will put Australia in the vanguard of global broadband development.

He believes any further delays in rolling out the broadband fibre network will prove a costly decision in the long-term.

"I think you know it's nearly criminal if the Opposition would indeed do that," he said.

"We have spent three years on getting where we are now.

"[The Coalition] is winding the clock back five years - because we have to start all over again with submissions, with all sorts of proposals, discussions and we already know that we are running years behind other countries in relation to broadband affordability and high-speed connectivity."