Condoleezza Rice struck a conciliatory note in the first speech of a four-nation European tour designed to heal the transatlantic rift caused by the Iraq war but overshadowed by concerns over secret CIA torture prisons.

After meeting newly-elected German Chancellor Angela Merkel in Berlin, the United States Secretary of State told a press conference that the United States "does not condone torture".

She added: "This is a war in which intelligence is the absolute key to success ... to get to perpetrators of such crimes before they commit them."

The comments were seen as reining back the sentiments of a speech given yesterday in which Dr Rice challenged European leaders to back "rendition" - the CIA's extrajudicial seizure, transportation and interrogation of thousands of terror suspects.

The lighter note was warmly welcomed by Frau Merkel who is anxious to repair frayed relations with Washington, caused by her predecessor Gerhard Schroder's outspoken opposition to the Iraq war and subsequent refusal to send in troops.

In comments that were notably supportive, Frau Merkel said: "We have to face the challenges of the 21st century... but we have to strike a careful balance. We have to stay in line with the laws we believe in and work together as close partners and friends".

The controversy follows international concern over the CIA's continued failure to confirm or deny suggestions that it has illegally abducted terrorist suspects and flown them between a network of European detention centres - so-called "black sites" - for interrogation under torture.

The CIA is alleged to have made hundreds of secret flights over Britain, Germany, the Netherlands, France, Sweden, Denmark and the Irish Republic. Der Spiegel, the German magazine, has claimed that 437 CIA flights landed in or crossed German airspace.

Dr Rice today said that she and Frau Merkel had discussed the reports although she again refused to be drawn on the existence of the prisons.

She said: "The United States does not condone torture. It is against US law to be involved in torture or to conspire to commit torture and it is also against the US’s international obligations."

Frau Merkel appeared to set the tone for the future relationship between Germany and the US when she challenged the US Secretary of State over the case of German national Khaled Al-Masri, which has become a major issue in the German media.

Lebanese-born Herr Al-Masri was allegedly seized by the CIA as an al-Qaeda suspect while on holiday in Macedonia in 2003. He was then flown to a prison in Afghanistan where he was held in jail for five months until the Americans realised they had got the wrong man.

Dr Rice said she could not comment on individual cases, but added: "In every policy, mistakes will be made."

After raising the issue in public, Frau Merkel said that she would ask her foreign minister, Frank-Walter Steinmeier, to investigate and report back in confidence.

Dr Rice also pledged to help trace Susanne Osthoff, a 43-year-old German aid worker who has been missing in Iraq since November 25. The kidnappers had reportedly set a deadline of Friday for Germany to stop training Iraqi police as the price for her release.

Roger Boyes, The Times correspondent in Berlin, said that the warm welcome given to Dr Rice suggested that relations were likely to grow closer, but that thorny domestic issues between the two nations over Iraq remains.

He said: "The fundamental cause of the bust-up between the US and Germany - Germany's refusal to send troops to Iraq - will not go away. The present foreign minister Frank-Walter Steinmeier was the chief of staff in Gerhard Schroeder's government and was deeply involved.

"However, the Germans will welcome the new friendlier tone and the new emphasis appears to be on a foreign policy relationship based on shared values.

"By raising the issue of al-Masri, Frau Merkel showed that she was not afraid of making forthright statements in public if that is needed, but the technicalities of the report - which will be made by the secretive parliamentary committee - are unlikely to become public.

"So she has also displayed a willingness to be discreet, unlike Gerhard Schroeder, who upset George Bush by using his opposition to Iraq to win a difficult election at home."

Dr Rice was due to fly on later today to visit Romania, named by human rights groups as one country that has played host to secret prisons, to sign an accord allowing US military bases to be based on its territory.

She is then due to visit the Ukraine and Brussels.

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