In a statement published on Monday, a foreign office spokesman said Yan Busch’s lectures were deemed to contradict “the interests of our national security and the people" of Belarus.
German embassy officials said Busch was deported from the former Soviet republic on Saturday because of his work with the Organisation of Young Democrats.
"These were seminars for young people during which they learned how to think independently [of the authorities] and make their own decisions," the project's director Vladimir Shantsev told journalists.
Shantsev added he suspected some of those who attended were being monitored, but that Busch's deportation was still surprising.
Ten year rule
Lukashenko earlier this month said he would not leave his post in 2006 if he felt his former Soviet republic was still going through tough times.
He suggested introducing a national constitutional referendum that would allow him to run for a third term as president. In 1996, a controversial vote extended his term by an extra two years until 2001.
Busch’s lectures "contradict the interests of our national security and the people"
Belarus foreign ministry
Lukashenko has ruled Belarus since 1994. During that period the republic's economy has suffered, obtaining minimal investment from the West.
The government has also closed several independent newspapers and deported journalist with a Russian television station whose coverage could be picked up in Belarus.
Belarus is the only European country not to have been accepted into the Council of Europe, despite applying for membership in March 1993.
The Council bases its refusal to accept the country on the lack of an independent judiciary and democratic control over the executive.