US President George W. Bush insisted Tuesday that his proposal to combat illegal immigration by deploying some 6,000 National Guard troops along the US-Mexico border will not compromise efforts to fight terrorism and other military programs.

"The up to 6,000 Guard in the first year of operation really is not going to put a strain on our capacity to fight and win the war on terror, as well as deal with natural disasters," Bush said at a press conference following his meeting with Australian Prime Minister John Howard.

"We'll be working in conjunction with governors to make sure that that's not the case, that it doesn't put unnecessary strain on other functions of the Guard," the president said.

Bush, in a speech late Monday proposed sending up to 6,000 National Guard troops to the border beginning next month.

Opposition Democrats have expressed concerns that deploying the National Guard along the US southern border would further stretch the US military that is under pressure from campaigns in Iraq and Afghanistan.

Officials from the US Defense Department and the Department of Homeland Security on Tuesday were holding briefings on the president's proposal.