Belfast City Council stockpiled 48,000 litres of extra fuel for its crematorium in case a crash-out Brexit disrupted supplies.
The procurement of the Liquefied Petroleum Gas (LPG) late last year cost almost £18,000 plus VAT.
It is almost 10 times the volume of LPG normally stored as a back-up to power the crematorium at Roselawn on the outskirts of the city.
The council said the purchase was a "contingency measure" as it prepared for the UK potentially leaving the European Union without a deal.
The details were revealed to Belfast Live in a freedom of information request.
A withdrawal agreement was eventually struck between the UK and EU which included a transition period lasting until the end of this year.
Negotiations are continuing between London and Brussels on a possible trade deal.
The chair of the city council's Brexit committee said "significant concerns remain" on how trade will operate after the transition period.
Green Party councillor Anthony Flynn said: "I fully support the work of our team at the crematorium who, under difficult and uncertain circumstances made all necessary preparations in anticipation of a possible no-deal Brexit.
"These preparations were made to ensure the council could continue to provide its critical services to the people of Belfast, which I fully support."
He added: "Significant concerns remain in relation to the port of Belfast and the level of checks that will be required post the end of the transition period, as well as concerns over the shared prosperity fund and how that will be provided.
"We need urgent clarity from the UK government and the EU on both of these vital issues, so that we can get on with providing key services and building back better post the end of the transition period and post-pandemic."
Belfast City Council said the crematorium is normally powered by piped natural gas.
A spokesman said: "We also have bulk tanks of Liquefied Petroleum Gas to be used as a back-up supply in cases of emergency. We normally store approximately 5,000 litres in these tanks."
On whether extra stocks are still needed for the end of the transition period, he added: "Belfast City Council has no specific information regarding the fuel supply chain and purchasing the additional liquefied petroleum gas was a contingency measure at that time."
The council had outlined its no-deal Brexit concerns and contingency plans in a series of internal reports, it emerged last year.
Concerns included a backlog of bin waste, loss of trade for businesses and food shortages for animals at Belfast Zoo.
The council said it has not stockpiled animal foods in preparation for Brexit, as its suppliers "have confirmed that they have no issues getting the relevant food items".
