German Foreign Minister Joschka Fischer has dismissed opposition claims that a lax visa policy allowed east European criminals to flourish in Germany.
Joschka Fischer has been strongly backed by Chancellor Schroeder
In a live televised speech, he told a parliamentary inquiry that the opposition claims were "propaganda".
The crime statistics, he argued, showed no increase in Ukrainian offenders.
The opposition says his ministry allowed an influx of prostitutes, drug dealers and gangsters from eastern Europe by relaxing visa rules.
The BBC's Berlin correspondent says the claims have hit the government hard.
It is the first time a German minister has testified live on television before a parliamentary inquiry.
"The theory that security was endangered, that the country was flooded with criminals, is simply a propaganda theory of the opposition," he said.
Previously one of Germany's most popular politicians, his reputation has suffered enormously from the allegations, the BBC's Ray Furlong says.
Mr Fischer's Green Party is a junior partner of Chancellor Gerhard Schroeder's Social Democrats (SPD).
The conservative Christian Democrats charge that new, more liberal, visa rules drawn up by the ministry four-and-a-half years ago allowed 300,000 Ukrainians to come to Germany as tourists - but that many were engaged in illegal activities.
Mr Fischer will be cross-examined by Christian Democrat members of the parliamentary inquiry, who will ask him why he ignored concerns voiced by German embassies.
Slow to act
He has acknowledged errors in his handling of the issue, but says he will not resign.
"I should have been informed sooner and I have should reacted sooner. That was my mistake," he told the inquiry.
The claims of soaring crime levels followed media reports that mafia gangs had developed a business of paying unemployed Germans to pledge to support visiting tourists.
The German authorities did not check to see if these Germans were financially capable of doing so.
A telephone poll of television viewers suggested that only 30% of them found Mr Fischer's evidence believable.
The architect of Germany's visa policy, Ludger Volmer, testifying last week, rejected the opposition accusations.
Mr Volmer, a former junior minister, also denied his directive had led to people-smuggling, saying it had been aimed at reuniting families divided by the Cold War.
But current and former German ambassadors testified that they had reported a rush of visa applications as early as March 2000.