The Whitegate oil refinery in Cork requires an investment of $400 million over the next four years, according to an information memorandum which has been circulated to potential buyers.
The refinery, which is 50 years old, requires the capital injection for modernisation and to allow it to diversify its product range, particularly into fuels with lower emissions.
The refinery has already been involved in the research and development of biofuels.
Whitegate is being sold by US energy giant ConocoPhillips, which no longer considers it a core asset.
While small by world standards, a shortage of refining capacity globally means the Whitegate refinery should attract significant interest.
According to the memorandum, Whitegate achieved an operating profit of $67 million on turnover of just under $2 billion in 2006.
This compares with an operating profit of $47 million in 2005 on turnover of $1.7 billion.
Its earnings after taxation and financing costs were stripped out amounted to $23 million last year.
It is understood that ConocoPhillips is projecting an operating profit of more than $100 million for 2007. This is based on an improved refining margin, helped by rising oil prices.
Sources say ConocoPhilips believes the facility, which sits on 327 acres of land, could be worth up to €350 million.
Topaz Energy, which owns the Statoil and Shell networks of petrol stations in Ireland; Canada's Irving Oil; and Switzerland-based Petroplus are believed to have expressed an interest in acquiring Whitegate.
Bids are expected to be lodged in July. Deutsche Bank in London is handling the sale.
Ninety per cent of Whitegate's output is sold in Ireland with the balance supplied to European markets.
Topaz is believed to be its biggest customer.
Whitegate was sold by the state to Tosco in 2001, with a stipulation that it must remain open for at least 15 years. Tosco is now part of ConocoPhillips.
ConocoPhillips, which is listed in New York, plans to retain ownership of the Whiddy Oil Terminal in Bantry Bay.
