A substantial office block rented by the Revenue Commissioners in Limerick city since the 1980s is to be the surprise lot to be offered for sale at the next Allsop Space auction in the RDS, Dublin, next Tuesday.

River House, a 3,307sq m (35,600sq ft) block at Charlotte Quay in the city centre, attracted considerable interest when it was recently offered for sale by private treaty. There were apparently several offers for the investment – the highest at €3 million – but a sale was not completed. The new reserve range set by Allsop Space for the auction will be €2.6 to €2.8 million.

Robert Hoban said the vendor had now chosen the auction system as the most transparent method to bring the sale to a head while also opening up the final stages of the sale process to the wider auction audience. "The fall of the hammer will provide a binding agreement in the fairest manner for all parties concerned," he said.

Revenue recently signed a new 10-year lease, which includes break options in 2018 and 2020. The current rental income of €345,320 is due to rise incrementally each year up to 2016 when the figure will be €370,952 .