The National Gallery of Ireland has received a donation of both £500,000 and a 17thcentury Dutch painting from the businessman Mr Lochlann Quinn and his wife, Brenda.
A personal gift from the couple, the money is intended to assist the completion of the gallery's 4,000 sq ft extension in Clare Street.
Work on the building has been delayed, but is now expected to conclude later this year before opening to the public next January.
The Quinns' donation is not the largest offered to the project: in February 1999 the head of Glen Dimplex, Mr Martin Naughton, and his wife, Carmel, who is chairman of the NGI, gave £1 million to the extension fund.
Other smaller sums have also been provided by individuals during the intervening period.
The painting given by the Quinns, A Musical Party by Gerrit van Honthorst, has been presented to the gallery under Section 1003 of the 1997 Consolidated Taxes Act. This provides for a credit against tax liabilities where the taxpayer donates certain heritage items to the national collections.
Last month two other paintings were withdrawn from auction in London and offered anonymously to the NGI under the same terms.
This is the first example of van Honthorst's work in the gallery's holdings. The picture is particularly significant because it had been brought to this country from Rome in the mid-18th century by the first Earl of Charlemont who hung it in his casino at Marino in Dublin.
The earl's descendants sold the work at auction in 1892, and its whereabouts were subsequently unknown until it reappeared recently in London. The picture goes on public display from today in the gallery's north wing.