Forecasters have warned of overnight temperatures plummeting as low as minus six degrees as the big freeze continues.

The cold snap is expected to run until Christmas morning, with temperatures predicted to drop as low as minus eight in some inland areas on Tuesday night.

Parts of the south and east of the country could see rain and sleet, turning to snow by Wednesday afternoon.

Aine Brady, minister for older people, urged the elderly to take extra care during the current cold spell.

"While it can be expensive to heat the whole house, it is important that those rooms in use should be heated," she said.

Flights have also continued to be affected by the cold snap, with Ryanair experiencing delays in flights to Luton.

Aer Lingus said its morning flight to Milan has been delayed because the Italian airport is closed due to snow.

Passengers are being advised to expect delays and cancellations.

Bus Eireann said it was experiencing severe delays in the south-west, particularly Limerick and Kerry.

Meanwhile, freezing fog on Monday night made for treacherous driving conditions, with ice and black ice on many back roads.