Washington: US defense secretary Robert Gates on Thursday confirmed the reality of arrest of CIA informants in Pakistan who provided information to the American intelligence in the run up to the killing of Osama bin Laden.

"That's the real world that we deal with," Gates told a key Congressional committee when asked about such an arrest in Pakistan, but he did not confirm the report.

"I would say based on 27 years in CIA and four-and-a-half years in this job, most governments lie to each other. That's the way business gets done," Gates said in response to a question.

He said that even allies send spy here for espionage purposes, and this is even true for those countries which receive aid from the United States.

Gates and Admiral Mike Mullen, Chairman of the Joint Chiefs of Staff, were responding to Pak-specific question from Senator Patrick Leahy.

Pakistan's top spy agency ISI has arrested five CIA informants, including an Army major, who supplied information to the CIA ahead of the US operation that killed Osama bin Laden.