Germany has admitted that in 2008-10 it trained members of the security forces of Belarus - the country branded by the West as Europe's "last dictatorship".
The government in Berlin said it had believed at the time that Minsk was committed to "a process of democracy".
But it said the co-operation was halted after President Alexander Lukashenko was re-elected in 2010, amid claims that the poll was rigged.
Earlier, a German newspaper said the training continued until 2011.
The Tagesspiegel daily reported that Belarus' security forces accompanied German police as observers during an anti-nuclear demonstration in Germany in 2010.
It also said that German officials also travelled to Belarus to train some 400 local border guards.
|Mr Lukashenko has been |
in power since 1994
"The German government intensified its dialogue with the Belarusian government between 2008 and 2010," German Interior Ministry spokesman Philipp Spauschus told reporters on Friday.
He said it was "because there were signs that Minsk was ready to implement democratic reforms and conform to rule of law.
But the spokesman said that - contrary to the Tagesspiegel's report - the "co-operation with the Belarusian government was largely reduced, leading to a total freeze" after the 2010 election in the former Soviet republic.
Mr Lukashenko won his fourth consecutive term in the election, which was described by the West as a charade.
Mr Lukashenko was also accused of persecuting his political opponents - a claim he denied.
More than 600 people - including four opposition candidates - were detained after the poll, amid street protests.
Earlier this year, the European Union extended its blacklist of Belarusian officials, adding 21 names to the list, which already included more than 160 individuals.