The letter, which has yet to draw a response from the White House, was written in light of the decision last month by Attorney General Eric Holder to appoint a prosecutor to investigate claims that officers of the Central Intelligence Agency and contractors working for the agency had used interrogation methods that had not been officially approved.
According to Radio New Zealand
such methods included the use of a power drill and making death threats to detainees.
However the seven former CIA chiefs, the BBC
confirms that they served both Republican and Democrat Presidents, who penned the letter to President Obama are concerned that the agency's effectiveness will be undermined by the inquiry.
Noting that lawyers from the time of the George W. Bush administration, who launched an investigation in to the alleged abuses, only prosecuted one case, the men who served as either Director of the CIA or Director of Central Intelligence, a position whose responsibilities included heading up the CIA, also questioned if other countries may be discouraged from sharing intelligence with the U.S. if they feared that the source of the intelligence would not be kept a secret.
In response to the letter sent to the President, which suggested that the inquiry "will seriously damage the willingness of intelligence officers to take risks to protect the country", risk-taking that in the writers' opinion is "vital to success in the long and difficult fight against terrorists who continue to threaten us", a spokesman for Eric Holder said that those who "acted in good faith and within the scope of the legal guidance given by the Office of Legal Counsel regarding the interrogation of detainees" would not be prosecuted.
President Obama has already stated that the decision to hold an inquiry was solely in the hands of Mr Holder.
says that the current Director of the CIA Leon Panetta, nominated for the position by President Obama, opposes the inquiry. However he was not among the signatories on the letter.
Those signatories include the last five men to serve as head of the CIA - Michael Hayden, Porter Goss and George Tenet, John Deutch and James Woolsey - as well as William Webster and James Schlesinger. Mr Schlesinger served as head of the CIA for six months in 1973, during the Presidency of Richard Nixon.