The average price of 300 litres of home heating oil in Northern Ireland has fallen to £238.30, its lowest since the Iran war began four months ago, according to the Consumer Council's weekly price checker.

The cost is down from £255.80 last week and well below the £382.97 recorded at the start of April. The average for 500 litres now stands at £380.96, compared with a peak of £612.37 on 9 April. A 900-litre fill averages £677.16, down from a high of £1,088.71 two months ago.

Prices vary by council area. Mid and East Antrim has the lowest average for 300 litres at £236.01, while Armagh, Banbridge and Craigavon is the most expensive at £241.49.

For 500 litres, Ards and North Down is cheapest at £374.97 and Newry, Mourne and Down most expensive at £389.72. A 900-litre delivery costs least in Ards and North Down (£666.50) and most in Derry City and Strabane (£692.15).

The price drops coincide with the signing of an initial peace deal between the US and Iran. The agreement provides for the reopening of the Strait of Hormuz, a $300 billion reconstruction programme for Iran, and the termination of all US sanctions. Negotiations over Iran's nuclear programme, the main stated reason for the conflict, are to be completed within 60 days.