A heritage scheme which allows donors to claim tax credits on items of national significance has helped the National Library of Ireland to acquire £2m worth of new collections in 2001. The library's annual review, published yesterday, says it had one of its busiest years, with new acquisitions coming from 'contrasting sides of the cultural spectrum'. One 'significant gift' highlighted by the library was a long letter from Roger Casement to a member of his family in January 1903, written on his return from an investigation of Belgian atrocities in the Congo.

One of the most important acquisitions was a 5,000-item collection of Sean O'Casey's papers, formerly owned by the playwright's family. The Educational Building Society paid £250,000 sterling for the collection, before donating it earlier this month under the tax credits scheme.

Among items purchased by the library this year was an extensive collection of papers generated over three centuries by the Leslie family of Glaslough, Co Monaghan. The collection was bought for a six-figure sum. Other acquisitions include the letters of Anthony Cronin to correspondents such as Myles na gCopaleen, Patrick Kavanagh and Francis Stuart, a previously unpublished and unrecorded archive of Yeats family letters extending over a 16-year period, and the papers of the late General Eoin O'Duffy, one of the founders of the Blueshirt movement and a member of the Irish Brigade, which he led in support of Franco's fascist movement in Spain.

Papers relating to the early days of the Abbey Theatre are contained in the newly-acquired archive of Thomas Keohler, who was a member of the theatre's business committee. Another acquisition is a collection of papers from members of the Fitzgerald family (Dukes of Leinster).