ARNOTTS, one of Ireland's best-known superstores, is to lay off two-thirds of its staff while it transfers to temporary premises during a major $1.47 billion three-year revamp of its Dublin city center stores.The company confirmed this week that 580 of its 950 staff are to be let go at its department store on Henry Street in Dublin. But the company pledged that numbers will rise again to more than 1,200 when the new development is completed in 2011.The upgrading of the Henry Street store is part of what's known as the Northern Quarter redevelopment plan for Dublin's north city center.Arnotts said it was hoped most of the layoffs would be voluntary, but the workers' main trade union, Mandate, was critical of the terms on offer and said it reckoned most redundancies would be compulsory. The union said workers were shocked at the number of jobs that will be lost by September. Union official Linda Tanham said the development of the Northern Quarter was coming at a huge cost to the workforce.Work on development of the Northern Quarter, a 150,000 square yard site which will include shops, 175 apartments, restaurants, bars and a hotel, is expected to start later this year.Tanham predicted there will be even further job losses. She pointed out that Arnotts has let space in its Henry Street property to over 30 other retailers. There wouldn't be sufficient space in the temporary premises at nearby Jervis Street to accommodate all the other retail shops that would be expected to move. Consequently the jobs of up to another 300 workers were at risk.Arnotts' chairman, barrister Richard Nesbitt, said the company regretted having to lay off people and the decision was not taken lightly.Arnotts started buying adjoining properties in 2004 as it began preparing the Northern Quarter plan. The proposal is said to be the brainchild of Nesbitt and fellow director and shareholder Niall McFadden.McFadden worked with Nesbitt on the buyout and delisting of Arnotts from the Irish Stock Exchange in 2003. He joined the board when it became a private company.