The economist who predicted that opening UK borders to 10 new EU countries in 2004 would increase the population by 13,000 a year has accused MPs of misinterpreting his figures.
Politicians have said the forecast was "spectacularly wrong" and "laughable".
But Prof Christian Dustmann believes none can have read his 2003 report.
He said it made clear immigration would be much higher if, as happened, Germany and other countries decided to curb access to their labour markets.
He told the BBC that at the time he was compiling the report, which was commissioned by the Home Office, "everybody expected" that "other countries, in particular Germany, would likewise open up their labour markets".
Although some Conservative MPs voiced fears when the report was published in June 2003 that Germany would seek to impose restrictions - and called for the UK to do likewise - Germany did not confirm its plans with the European Commission until November 2003.