The Regatta Quay development, which includes a 20-storey building known locally as the 'wine rack', was taken over by administrators in 2010.
The Irish government owns the site after buying Irish bank debts.
The administrators said completing the ??100m buildings was dependent on the property market.
Work on Regatta Quay started in 2007, but it stopped as City Living Developments (Ipswich) Ltd, which had borrowed from the Anglo Irish and Allied Irish banks, went into administration.
Ben Gummer, Conservative MP for Ipswich, said it was "almost a metaphor" for the British economy.
"It's property speculation gone mad and a banking system which is bust, so it's going to take a lot of time to put that right," he said.
"The administrators are actively trying to find a developer to take on the work, so things are moving now but I'd like to see them move quicker."
Baker Tilly were appointed administrators for Regatta Quay by Ireland's National Asset Management Agency.
The accountancy firm is also the administrator for The Mill development next to Regatta Quay.
Regatta Quay has 118 flats built, with space for 150 more in the 'wine rack'. The Mill has 194 completed and 140 uncompleted flats.
Nigel Millar, from Baker Tilly, said: "It's very difficult to say when building work could resume.
"We'll certainly be in administration for two years. How long we'll be in administration depends on how sales progress."
Savills, which is the estate agent for the sites, said sale prices for a two-bedroom apartment had dropped from about ??300,000 in 2008 to ??175,000.
Andy Redman, from Savills, said: "If we can continue to sell at the rates we're achieving of 3-4 flats a month, then it may bring things forward, but it's dictated by market conditions."

The firm collects data from thousands of smartphone owners via an app.
Of the four UK networks, EE was found to have the best 4G connectivity, while Three had the worst.
However, Three also had the fastest download speeds when it was connected to 4G, the researchers found.
Three was the last operator to roll out 4G in December 2013 and told the BBC it was continuing to extend its 4G network every day.
"Almost everyone now uses a mobile phone service and it's not good enough that the UK is lagging behind so many countries with our 4G network coverage," said Richard Lloyd, executive director of Which.
The State of the Mobile Network report also noted that O2 had the highest 3G and 4G latency - that's the amount of time data takes to travel along a network, measured in milliseconds.
The firms have committed to investing in mobile networks. Last year, EE unveiled a Â£1.5bn three-year network investment plan that included the expansion of 4G and the commitment to reach 99% of the population with "superfast 4G".
However, mobile phone providers have faced planning issues when creating the necessary infrastructure, said analyst Kester Mann from CCS Insight.
"Network operators will maintain that they are investing millions of pounds each day in network coverage and capacity to satisfy the insatiable demand for mobile data services among UK consumers," he said.
"They will also cite tough planning restrictions to allow taller masts to provide wider coverage, a challenge recognised in George Osborne's recent Budget.
"These findings show that, although the UK is a leading market in the uptake of 4G services, there is still plenty of work to be done in network roll-out."
Administrators say work will not resume on an unfinished block of flats on Ipswich waterfront until 96 completed apartments are sold.
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Smartphone users in the UK can only access 4G's data service about half of the time on average, according to a new report by OpenSignal and consumer watchdog Which.