US Defense Secretary Robert Gates met Thursday with president-elect Barack Obama's defense team, opening a more substantive phase of the political transition at the Defense Department.

Gates, who is rumored to stay on at the Pentagon after Obama takes office on January 20, met with the leaders of the Obama transition team, John White and Michele Flournoy, Pentagon spokesman Geoff Morrell said.

"It was a very positive meeting.... All involved are very committed to a smooth transition," he told reporters after the meeting on a flight taking Gates to Canada for a Friday meeting on Afghanistan.

"Their conversation covered a wide range of issues," Morrell said without elaborating.

"The secretary offered his insights on what he believes ... the early challenges might be for the next secretary and his team," he added.

"This is the first of what will likely be several meetings with the transition team."

Gates's office sent out guidelines Wednesday to Pentagon staff outlining the rules for interacting with a transition team that now numbers 16 persons, including several former members of president Bill Clinton's administration.

Members of the Obama team were expected to move out into various parts of the Defense Department to review policies, operations and procedures, but for now they will not have access to classified information on many of the most critical subjects involving the Pentagon.

According to the guidelines, these include current military operations; special access programs; pre-decisional budget information; contingency operations and plans; personnel records; privileged or legally protected information; sensitive acquisition information; and active National Security Council policy deliberations.

Transition team members who already have security clearances will have access to other classified information.

Pentagon spokesman Bryan Whitman said further guidelines expanding the level of access will be issued as the transition progresses.

Gates's future has been a subject of intense speculation since a top Obama foreign policy adviser, Richard Danzig, told reporters October 2 that Gates had been a good defense secretary and "would be a better one in an Obama administration."

The Wall Street Journal said earlier this month that Obama was leaning towards keeping Gates in office for at least a year even though other names have been thrown into the mix such as Danzig himself, or John Hamre, former assistant secretary for defense under Clinton.

Another likely candidate to the Pentagon spot is Vietnam veteran and Republican Senator Chuck Hagel.

Morrell refused to comment on the rumors.