The findings of the inquiry chaired by Lord Penrose - which had been due to be released this year - are now to be made public in March 2014, more than six years after the pledge to hold an investigation was made by the Scottish Government.
The delay will increase the overall cost of the inquiry, which to date has cost more than £9 million.
The delay has been caused by a decision to seek further written evidence from witnesses on the issue of trying to establish exactly how many NHS patients were affected, according to an inquiry spokeswoman.
This is the second major public inquiry to be delayed this month, as it was also revealed that the report from a public inquiry into the deaths from clostridium difficile at the Vale of Leven Hospital in West Dunbartonshire had been put back for a fourth time.
The Vale of Leven inquiry was originally due to be published by the end of May 2011, but it too is expected to report by the end of March next year.
Health Secretary Alex Neil said the chairman of the Vale of Leven inquiry Lord MacLean, who was struck by illness last year, required extra time in order to fully consider all evidence to ensure a robust report.
However, opposition politicians yesterday raised concerns about the delays affecting both inquiries.
Neil Findlay, health spokesman for Scottish Labour, said: "The people affected deserve to know what went wrong and it's unfair to make them wait this long while they have to live each day with the consequences of what happened to them.
"Public inquiries should bring closure to those affected and also bring forward recommendations to improve our systems.
"Questions must be asked of Alex Neil on why he hasn't pushed for both the Penrose and Vale of Leven inquiries to report sooner. The public need to know what is holding up these vital inquiries."
Scottish Conservative health spokesman Jackson Carlaw said: "As a party we believe that public inquiries, given their gravity and their expense, should only be established in the most deserving of situations.
"So when they are launched, it's important timescales are adhered to. Many were affected by these tragedies and are placing considerable store on the respective inquiry outcomes. Delaying them further can only extend distress and fuel suspicions."
The Penrose inquiry was set up to examine how hundreds of haemophiliacs and other patients were infected with HIV and hepatitis C through "bad blood" products during the 1970s and 1980s.
Bernard Manson, chair of the Haemophilia Society, said: "Those whose lives have been directly impacted by contaminated blood, who have waited 30 years for a public inquiry, will wish to see the report as soon as is practical.
"However, we understand why, with the large amount of evidence coming before the inquiry, Lord Penrose has felt it necessary to extend the time to produce his report beyond his original estimate.
"We look forward to the report and to the response of the Scottish Government."
Campaigner Bruce Norval, a haemophiliac who contracted hepatitis C from infected blood products, said he was "not happy" about any delay. However, he added: "If those delays are going to result in a proper, measured conclusion to this then I will tolerate them."
A spokeswoman for the Penrose Inquiry said: "Following the final procedural hearing held in October 2012, further work on statistics has led to an extended timescale for completion of the Penrose Inquiry's final report. However, it is now in its concluding stage.
"Subject to the length of time required for the warning letters process and the time to print the final document, it is anticipated that the final report will be published in March 2014."
A spokeswoman for the Scottish Government said: "The Penrose Inquiry is independent of Scottish ministers, and it is a matter for the chairman, Lord Penrose, to decide on how he wishes to progress the inquiry within the terms of reference."
The spokeswoman added that there was an intention to review the existing financial support provisions for people who contracted hepatitis C from NHS contaminated blood following the final report and recommendations of the inquiry.