Transpower could find itself blocked from accessing pylons in South Canterbury as a dispute with farmers comes to a head.
A number of landowners with pylons on their properties have become frustrated after four years of negotiations failed to deliver what they consider fair compensation for use of their land.
A meeting of the South Canterbury Federated Farmers pylon committee on Tuesday issued an ultimatum giving the power company seven days to reach an agreement or padlocks will be going on gates, the Timaru Herald reported.
Transpower spokeswoman Rebecca Wilson said major upgrade work on the Roxburgh-Islington line, which supplies Christchurch, had been completed, but critical maintenance work was still to be done on the foundations of about 20 towers.
Temuka farmer Jeremy Talbot told the newspaper he had closed his gates, allowing Transpower on his land only if there was an emergency.
"There is to be no more access given to allow that work to be finished until we finally do get the settlement we've been seeking."
Ms Wilson said landowners, who were being dealt with individually, had been offered "easement" payments, which some had taken up.
That offer remained on the table and the company was still negotiating.
"There's various factors that we need to still talk to the farmers about and we're continuing to negotiate with them."
Federated Farmers national electricity spokesman Philip York said the organisation did not condone the lockout and was continuing to work with Transpower, but he sympathised with the farmers.
"I can understand the frustration of these people being pushed into this position. There's about 20 pylons left [to be upgraded]. They're thinking that as soon as they finish these 20 then Transpower are just going to walk away and pretend the problem doesn't exist.
"So they're just protecting what they perceive as their rights."
Mr York said annual rental fees were paid to people with cellphone towers and wind farms on their land and overseas models included payment for power lines.
"As far as we are concerned, we'd like to think Transpower will be offering a modest annual payment."