The FBI has formally charged former Intel employee Biswahoman Pani with the theft of corporate secrets, including future processor designs and detailed schematics.

Special agent Timothy Russell of the FBI's Boston computer crime squad said that a search of Pani's house in July unearthed more than 100 sensitive Intel documents and 19 computer aided design files.

The affidavit states that Pani told his bosses at Intel that he was resigning and gave his leaving date as 11 June. He then used unused holiday to sit out his notice period.

Pani told his bosses that he was going to work for a hedge fund but in fact started work at rival AMD on 2 June and used his Intel laptop to access the company's servers and download commercially sensitive data.

An Intel employee found out about Pani's new job and informed management, who called in the FBI.

"Intellectual property is a critical asset for Intel," company spokeswoman Claudine Mangano told The Boston Globe.

"We basically asked the Department of Justice and the FBI to investigate the activities, and we are cooperating with that investigation."

Pani is not being held in custody but has been ordered to surrender his passport. He is no longer working for AMD, and there is no evidence that the company saw the secret documents or asked Pani to steal them, according to his attorney R. Bradford Bailey.

"My client vigorously maintains his innocence and plans to fight these charges in court," said Bailey.

The FBI is taking an increasingly tough line against staff stealing data from former employers, in the face of evidence suggesting that many employees are prepared to commit the crime.