Forecourt retailer Applegreen has confirmed that its business customers who use fuel cards have been informed of 'substantial' price increases for petrol and diesel, effective tomorrow.

It said the move will bring the price of fuel for business customers into line with the price already being paid by retail customers.

It is also understood that Certa, which owns 35 forecourts around the country, intends to increase its prices.

The price of oil on international markets remains at eight-year highs.

The increases at the pumps come as some home heating oil suppliers are restricting customers to 500 litres a fill in an effort to manage increased demand.

The President of the Irish Road Haulage Association (IRHA), Eugene Drennan, has also said some of its members are not receiving their normal level of diesel supplies.

Earlier, the IRHA wrote to the Government to raise ‘serious concerns’ about continuity of fuel supplies.

A statement from Fuels for Ireland, which represent fuel suppliers, said its member companies "have certainty of supply for the months ahead".

"We are completely confident that adequate supplies will continue to be provided to meet normal buying patterns."

Meanwhile, RTÉ News has learned that a consignment of oil from a Russian port in the Baltic is due to arrive in Dublin Port next Wednesday.

Ports in the UK have been turning away Russian registered vessels.

A spokesperson for Dublin Port was not available for comment.

In a statement this evening, the Department of Environment, Climate and Communications said "no shipments of oil into the State are currently being blocked, though all of this is under consideration".

The Department was responding to a query from RTÉ News about the imminent arrival of a tanker carrying oil from a Russian Baltic port on 9 March.

The Department’s statement also said that the "operational issues" around the release of oil reserves from the National Oil Reserves Agency (NORA) "are being worked through".

The Department said NORA currently holds just over 90 days of strategic oil reserves and that 85% of these supplies are held on the island of Ireland.

Additional reporting Will Goodbody