WASHINGTON - US President Barack Obama on Wednesday announced he has accepted the resignation of General Stanley McChrystal, commander of U.S. forces in Afghanistan, and is to nominate General David Petraeus, commander of U.S. Central Command, to take over the war in Afghanistan.

Flanked by Vice President Joe Biden, Defense Secretary Robert Gates, Chairman of the Joint Chiefs of Staff Mike Mullen and Petraeus, Obama announced the decision after an hour-long meeting of his advisers on Afghanistan war. He said the behavior of McChrystal, who made disparaging remarks about senior administration officials, was unbecoming.

"The conduct represented in the recently published article does not meet the standard that should be set by a commanding general," Obama said, noting it undermined civilian control of the military and the ability of the team handling the Afghanistan war to work together, emphasizing he "won't tolerate division."

"As difficult as it is to lose General McChrystal, I believe that it is the right decision for our national security," Obama said, telling troops they must obey conduct code, which applies equally to all military personnel.

After announcing he will nominate Petraeus, who is the immediate superior to McChrystal, Obama urged Congress to confirm the nomination as soon as possible. Petraeus served as commander of U.S. forces in Iraq during former President George W. Bush's troops surge there.

McChrystal was summoned to Washington to explain his remarks critical of Obama and other senior administration officials. He met with Gates in the Pentagon in the early morning, and then with Obama in the White House. Both meetings lasted around half an hour.

McChrystal was initially expected to join the monthly strategy meeting of Obama's Afghan war advisers in White House situation room, but he was not seen returning to the White House after the morning meeting with Obama.

McChrystal made the disparaging remarks to the Rolling Stone magazine. In a profile titled Runaway General, which is to appear in this week's magazine, McChrystal said he felt betrayed by U.S. ambassador to Kabul Karl Eikenberry. He recalled to the magazine the time he asked for more troops from Obama as "painful," and said Obama had him in "an unsellable position" to ask for an increase in troops.

Obama eventually decided to send 30,000 more troops to Afghanistan in December.

The magazine story also contained mocking remarks from McChrystal's inner circle of aides towards senior administration officials such as Biden and National Security Adviser James Jones.

After Obama made the remarks, McChrystal released a statement saying he offered his resignation out of a desire to see the mission in Afghanistan succeed, and he supports Obama's strategy and remains deeply committed to the war.

Afghan President Hamid Karzai, who voiced his support to McChrystal earlier, said through a spokesman he respects Obama's decision, and looks forward to working with Petraeus.

NATO Secretary General Anders Fogh Rasmussen said in Brussels the coalition's strategy in Afghanistan remains unchanged.