Vaclav Havel was among the targets

The dissidents were physically intimidated, harassed, threatened and harshly interrogated, with the aim of forcing them out of the country, the court heard.

About 20 of the targeted group asked the communist authorities to send them into exile, and were stripped of their citizenship.

The dissidents were targeted because they had created or signed the human rights manifesto - Charter 77.

'Sanitation'

The campaign, code-named "Asanace" - the Czech word for sanitation - continued from 1978 to 1984.

The three men - Vladimir Starek, Zdenek Wiederlechner and Zdenek Nemec - worked for the interior ministry and the secret police.

They could have been jailed for up to 10 years.

Former Interior Minister Jaromir Obzina was also charged over the affair, but charges against him were transferred to the Supreme Court, which will decide if they can be pursued because of his parliamentary immunity.

Another defendant, Oldrich Mezl, was acquitted because no documents were found signed by him.

In a related case, two former secret police agents were jailed on Monday for three years for torturing dissidents.