Thousands of vulnerable people in Wales could be missing out on Cold Weather Payments because of the way eligibility is assessed, it has been claimed.
Arfon MP Hywel Williams said because temperature readings are made in warmer low-lying coastal areas, those on hills and valleys in Wales miss out.
The £25-per-week payments are made when it is below 0C for seven straight days.
The UK government said weather stations were linked to postcode areas to provide the most stable readings.
Last winter, 244,000 people in Wales were eligible for the cold weather payout, including many pensioners and those with disabilities.
To qualify, householders have to be claiming one of five benefits – Pension Credit, Income Support, Income-based Job Seekers’ Allowance, Income-related Employment and Support Allowance, or Universal Credit.
But Mr Williams said payment eligibility for people in his mountainous constituency is based on the temperature 20 miles away at Mona on Anglesey.
Llion Price, an elderly man living in Deiniolen – a village perched on a hillside facing Snowdon – said he only received one payment last winter, despite what he described as consistently freezing temperatures in the village.
“It doesn’t make any sense whatsoever,” he said.
“It’s completely different weather on Anglesey, compared to here.”
Mr Williams will introduce a Private Members Bill in the Commons next week calling on the UK government to carry out an annual review of the system and said he has cross-party support.
“Many vulnerable people in my Arfon constituency and indeed across Wales have repeatedly missed out on the winter payment because of this basic fault in the system,” he said.
“The temperature for upland settlements in Arfon as well as for Ynys Mon is measured on the sea shore at Mona, where it is consistently warmer.”
A Department of Work and Pensions spokesman said: “The scheme links postcodes to the weather stations that provide the most stable and accurate readings for average temperatures.
“Each year we review the scheme, seeking expert advice from the Met Office, taking into account representations from MPs and the public.”