The Swiss government has granted permission for overflights by non-commercial United States aircraft until the end of 2006.
Previously the government had only extended the rights until the end of January as it was waiting for a response from Washington concerning CIA planes carrying prisoners.
The Swiss foreign ministry and the environment, transport, energy and communications ministry issued the permit on Wednesday after receiving requested clarifications, government spokesman Oswald Sigg confirmed.
These clarifications – in addition to explicit assurances – were provided by the US authorities on January 30, said Sigg, who added that the overflight licence could be withdrawn at any time.
The US authorities stated officially that they had used neither Swiss airports nor airspace to transport prisoners. They added that they had always respected Swiss sovereignty in the past and would continue to do so in the future.
The new permit is also intended to simplify proceedings. In addition to the United States, 25 other countries and two international organisations have been granted a general overflight licence until the end of the year and they can now fly over Switzerland without having to apply for a separate permit each time.
The Swiss authorities retain the right however to intervene and run checks in suspicious circumstances.
On January 31 a parliamentary sub-committee cleared the Swiss cabinet of having knowledge about alleged overflights in Swiss airspace of CIA planes carrying prisoners.
The committee added that the government had no evidence of illegal flights or the existence of CIA detention centres in Europe.
Only in one case was there any reason for suspicion, said the head of the sub-committee.
This involved a plane which flew across Switzerland twice on the same day two years ago – between Ramstein in Germany and Milan – reportedly carrying Abu Omar, a radical imam abducted by the CIA.
The Swiss Federal Prosecutor's Office is still investigating the case.
Swiss senator Dick Marty, who is heading an investigation into the affair for the Council of Europe and who released an interim report last week, cast doubt on the US statement.
"I hope the cabinet took into account the Milanese prosecutor's files regarding the abduction of Abu Omar," he said, pointing out that the air traffic control body Skyguide confirms that the flight in question flew across Switzerland twice.
"If you don't want to look at the evidence, then you won't see it," he said.
The US assurances were also received guardedly by Swiss political parties.
"It's good if it's indeed the case," said Fulvio Pelli, president of the centre-right Radical Party.
Ueli Maurer, president of the rightwing Swiss People's Party, did not want to comment on the US pronouncements but saw no reason not to believe them.
swissinfo with agencies
June 2004: Human Rights Watch claims that the US is detaining alleged terrorists at more than a dozen secret locations around the world.
November 2, 2005: The Washington Post reports that the CIA is detaining members of al-Qaeda in eight eastern European countries and Asia.
January 8, 2006: The SonntagsBlick newspaper claims to have intercepted a fax from the Egyptian government confirming the detention centres.
January 31, 2006: A parliamentary sub-committee clears the Swiss cabinet of having knowledge about alleged overflights in Swiss airspace of CIA planes carrying prisoners.
At least 73 flights were made over Switzerland by US planes suspected of being used by the CIA between 2001 and December 2005, according to the Swiss Federal Civil Aviation Office.
Four of these flights touched down in Geneva.
In compliance with the JTI standards