His comments came as his top security advisor said there was no evidence so far that the Pakistan Government knew about the Al-Qaeda chief's presence in the country.
"We think that there had to be some sort of support network for bin Laden inside of Pakistan," Obama told the CBS show ''60 Minutes'' in his first public comment on the issue.
The US called on Government of Pakistan to conduct an investigation into how Osama was able to live so long in a military cantonment area of Pakistan, in an affluent suburb of Islamabad.
"We don't know whether there might have been some people inside of [Pakistan's] government, people outside of government, and that's something that we have to investigate and, more importantly, the Pakistani government has to investigate," Obama said.
Obama said the Pakistani Government has indicated that they have a profound interest in finding out what kinds of support networks bin Laden might have had.
"But these are questions that we're not going to be able to answer three or four days after the event. It's going to take some time for us to be able to exploit the intelligence that we were able to gather on site," he said, according to the excerpts.