In response the States is looking at options to offer extra support to some households.
It is estimated the rise will cost customers as an extra £10 to £15 per month.
Islands Energy Group, parent company of Guernsey Gas and Jersey Gas, made the announcement following significant global increases in the cost of all forms of wholesale gas.
In Guernsey, a permanent price increase of 2.2% is to be applied, with an additional, market-linked increase of 14.7% added to it.
This will be reviewed in six months and may be reduced if global market conditions allow.
IEG CEO Jo Cox said this was not a decision it had taken lightly.
‘But having explored all our options we are left with only this difficult choice,’ she said.
‘The price of wholesale gas has doubled as energy markets are reacting to a variety of complex influences including a significant number of events across the world, such as Brexit, Covid, storms across America, and unpredictable weather globally.
‘It is a wide range of factors that have combined to affect supply chains in a variety of ways, increasing the cost of many things that are crucial to the supply of gas.'
In Jersey, prices will fall 2% from the current level from mid-October. But an additional, market-linked increase of 15.2% is being brought in at the same time, and will be reviewed and may be reduced after six months if market conditions allow.
Environment & Infrastructure president and Employment & Social Security vice-president Deputy Lindsay De Sausmarez has been in contact with IEG.
‘IEG have kept me well informed of the emerging situation and its consequences locally and, although I’m reassured that the supply of gas will not be impacted, I am obviously concerned about the effect this unavoidable increase in cost will have on islanders who rely on gas, particularly for heating their homes with the colder months on the near horizon,’ she said.
‘I’m in active dialogue with the presidents and officers of both Employment & Social Security and Policy & Resources to explore options to provide the additional support some Guernsey householders may need to afford their gas bills once these price rises take effect.
'We will communicate the details as soon as we can.’