An opencast coal mine in the south of Powys could be re-opened, safeguarding 100 jobs, its operators say.
Nant Helen near Ystradgynlais had permission to operate until the end of 2018 but was mothballed in 2016.
It followed a drop in demand for anthracite coal from Aberthaw power station in the Vale of Glamorgan.
Celtic Energy said it needed to resume mining at Nant Helen for another three years to replace supplies running out at nearby East Pit, which is closing.
Under the current permission dating from 2012, mining at Nant Helen was supposed to stop by 31 December 2018.
Work restoring the site is due to finish by the end of June 2021, according to the Local Democracy Reporting Service.
The company now wants to extend its mining operation until the end of 2021, with restoration to be completed by the end of June 2023.
A report to Powys county councillors by regional mineral and waste planning manager Hugh Towns says restarting production at Nant Helen would help to support the local economy.
"There will also inevitably be indirect jobs in support industries," he added.
"The importance of these jobs in this area should not be overstated given that part of Ystradgynlais is within the top 10 per cent of the most deprived areas in Wales."
Ystradgynlais Town Council has discussed the application and accepts that work needs to start again but had "strong concerns" about the restoration work.
The town council believes that a 30-metre deep lagoon would be "unacceptable", claiming it would endanger Caerbont near the town.
Powys councillors are due to consider the bid to resume mining on Thursday.