The future of Thom's Dublin street directory, which has been published in the city for over 150 years, is in serious doubt according to its owner, Irish Press Plc.

The company is confident it can publish a 2006 edition of the directory, but is unlikely to continue publishing the famous directory after that.

The directory is used by a wide range of companies and individuals, and is very popular with tourists trying to research their family history.

People buying period homes also use the guides to find out who may have lived in their house in previous decades. Libraries around the country stock the guide and local historians draw on it for research purposes.

Irish Press, which owns Thom's Publications Limited, said the Electoral Act meant it could only access an edited version of the electoral register, not the full version. It said this made it difficult to keep residential data up to date.

The company said representations to the Minister for the Environment on the issue had been "sympathetically received", but there was no sign of any changes being made.

The loss of the publication would bring to an end one of the longest running publishing ventures in Ireland. An earlier version of the directory first appeared on the street in 1752 at a price of three pence.

According to the contents at that time it contained "no inconsiderable list of merchants, with some eminent grocers". In 1844 this guide became the property of Alexander Thom, who owned a thriving printing business in Dublin. His father Walter Thom had edited and published the Dublin Journal. In 1960 Thom's Dublin Street Directory and Thom's Commercial were first published as separate directories. Since then the directories have been revised and updated each year.

The current Thom's for Dublin lists some 11,599 streets.

The Thom's directories are now available for several cities and towns outside Dublin, including Cork, Galway, Limerick and Athlone.