By Bethany Bell
BBC News, Vienna
The European security body, the OSCE, has said human rights must not be allowed to become a casualty of the fight against terrorism.
The OSCE promotes democracy and human rights in Europe
At a meeting in Vienna, the UN's expert on torture said the consensus against torture appeared to be weakening when it came to fighting terrorism.
The gathering began with a moment of silence for the victims of last week's attacks in London last week.
The meeting in the Austrian capital had been planned for some time.
The head of the OSCE's Office for Democratic Institutions and Human Rights, Christian Strohal, said the response by the UK authorities and public to the attacks had given a clear message that terrorist acts must not undermine the values of democratic society.
But he said human rights were in danger throughout the OSCE region.
"Terrorism in itself is a terrible negation of practically all human rights and therefore we shouldn't give terrorists the satisfaction that they are progressing with their terror play."
The United Nations special rapporteur on torture, Manfred Nowak, told the meeting that the use of torture in fighting terrorism was unacceptable.
He warned that the international consensus against using torture now appeared to be put into question for the first time since World War II.