Washington, Aug 19 (DPA) The final US combat troops departed Iraq early Thursday, ahead of schedule to complete a key phase of President Barack Obama's plan to withdraw, US media reported.

An NBC television correspondent embedded with the US Army's 4th Stryker Brigade Combat Team, reported the troops began crossing the border into Kuwait at 1:30 a.m. (2230 GMT Wednesday).

The US military kept the departure under wraps until early Thursday. A Washington Post reporter present at the brigade's departure reported the military required the accompanying media to maintain secrecy until the brigade reached Kuwait.

The brigade's departure came more than seven years after the March 2003 invasion to topple Saddam Hussein's regime. The most recent Pentagon figures showed 4,415 US soldiers have died in the conflict.

The 4th Stryker Brigade Combat Team, 2nd Infantry Division, is based at Fort Lewis, Washington. A spokeswoman at the base could not confirm it had left Iraq but said plans were underway to have the troops back home by mid-September.

Obama had set an Aug 31 deadline for withdrawing US combat troops from Iraq, which would reduce the American presence to about 50,000 responsible for training Iraqi security forces and assisting in counter-terrorism operations.

US commanders opted to drive the combat troops out over a 580-km journey instead of flying them out to keep the last combat force in country several weeks longer, the Post reported.

All US forces are scheduled to leave Iraq by the end of 2011 as Obama shifts the focus to the war in Afghanistan. During his presidential campaign, Obama pledged to end the US role in Iraq, a war he opposed and said was draining resources from the fight against the Taliban and Al Qaeda.

The end of the US combat role marks a major shift for the Iraqi government, which has been taking on a greater responsibility for security operations.

The top US commander in Iraq, Ray Odierno, had said that a recent uptick of violence and the political stalemate in the Iraqi government following March parliamentary elections would not delay ending the combat role.

A recent upsurge of violence includes more than 80 people just in the last week, including 58 killed Tuesday when a suicide bomber blew himself up outside an Iraqi army recruiting centre in Baghdad. US officials say Al Qaeda in Iraq is severely weakened and the recent spate of attacks is a desperate attempt to show it has a presence in the country.

Tens of thousands of US soldiers have been leaving Iraq this year and hundreds of bases were transferred to the Iraqi government. The US military has expressed confidence that the Iraqis are capable of assuming security responsibilities.

US State Department spokesman PJ Crowley told MSNBC that even as the combat mission comes to a close, the United States will have a long-term commitment to Iraq as the missions from a military led campaign to a diplomatic one.

"We are ending the war ... but we are not ending our work in Iraq. We have a long-term commitment to Iraq," he told MSNBC.