BBC:

Twenty-six Americans and six Italians are accused of kidnapping an Egyptian terror suspect and sending him to Egypt, where he was allegedly tortured.The Americans - most believed to be CIA agents - will be tried in absentia. Italy has not announced if it will seek their extradition to the Milan trial.

US President George W Bush will arrive in Italy hours after the trial opens.[..]

Italy's government has asked the country's highest court to set aside the rendition trial, saying prosecution documents will break state secrecy laws and damage relations with the CIA.[..]

One of the surprise witnesses in the case will be Philip Morse - one of the minority owners of the US baseball team the Boston Red Sox, says the BBC's Christian Fraser in Rome.

It is alleged that his Gulfstream jet was used by the CIA to fly Abu Omar out of Italy, says our correspondent.