Top members of the Bush administration and President-elect Barack Obama's staff teamed up at the White House Tuesday for a joint exercise on how to handle a possible terrorist attack.

The drill was part of an effort to ensure a smooth transition of power from Mr. Bush to Mr. Obama on January 20 - the first such transition to take place since the terrorist attacks of September 11, 2001.

During the exercise, the officials responded to a scenario in which transportation facilities and other targets in several cities were hit with explosions.

The White House said the drill was purely hypothetical and was not based on any current, credible threat.

Rahm Emanuel, Mr. Obama's designated chief-of-staff, said before the event that partisan divisions had been set aside because, at the end of day, both teams work for the American people.

Current White House chief of staff Joshua Bolten said the Bush administration began consulting with both Democratic and Republican presidential campaigns last summer on a number of issues.

He said that close consultations with the incoming team started shortly after Barack Obama's November 4 election victory.

Bolten said after the election close to 1,000 members of the Obama transition team received access to information and briefings at nearly 100 government agencies.  He said the Bush administration also expedited clearances for key members of Mr. Obama's national security team. 

Some information for this report was provided by AFP and AP.