U.S. Secretary of State Condoleezza Rice called Tuesday for the "immediate and unconditional release" of Zimbabwean opposition activists detained after being attacked by security forces during a prayer meeting.
Rice said the United States holds President Robert Mugabe responsible for the safety and well-being of those in custody.
They include Movement for Democratic Change leaders Morgan Tsvangirai and Arthur Mutambara, and National Constitutional Assembly leader Lovemore Madhuku.
"The world community again has been shown that the regime of Robert Mugabe is ruthless and repressive and creates only suffering for the people of Zimbabwe," Rice said.
Two days after the attack, about 50 activists detained in the Sunday crackdown appeared in court. Many were bandaged and bruised, reports AP.
At the State Department, deputy spokesman Tom Casey called on the international community to take a "hard look" at the crackdown.
"It's up to individual countries to act," he said.
The choice of the city of Helsinki is not incidental as the capital of Finland had hosted US-Soviet negotiations on the limitation of nuclear stockpiles in 1969