BERLIN, April 21 -- European prosecutors are likely to investigate CIA and Bush administration officials on suspicion of violating an international ban on torture if they are not held legally accountable at home, according to U.N. officials and human rights lawyers.

Many European officials and civil liberties groups said they were disappointed by President Obama's opposition to trials of CIA interrogators who subjected terrorism suspects to waterboarding and other harsh tactics. They said the release last week of secret U.S. Justice Department memos authorizing the techniques will make it easier for foreign prosecutors to open probes if U.S. officials do not.

Some European countries, under a legal principle known as universal jurisdiction, have adopted laws giving themselves the authority to investigate torture, genocide and other human rights crimes anywhere in the world, even if their citizens are not involved. Although it is rare for prosecutors to win such cases, those targeted can face arrest if they travel abroad.