President Bush opened the door for the first time yesterday to the idea of shutting down the U.S. prison camp at Guantanamo Bay, Cuba, a facility that has become a symbol of excess for critics of the United States around the world since it was opened after the attacks of Sept. 11, 2001.

While Bush continued to defend the treatment of prisoners at the camp, he pointedly did not rule out suggestions by two leading Democrats that the facility be closed in an effort to repair the tarnished U.S. image abroad. "We're exploring all alternatives as to how best to do the main objective, which is to protect America," Bush told Fox News Channel when asked about the prospect. "What we don't want to do is let somebody out that comes back and harms us."

The president's comments surprised many in the administration and Defense Secretary Donald H. Rumsfeld seemed to shoot down the notion, telling reporters flying with him to Europe that he was unaware of any consideration being given to shutting down Guantanamo Bay. Officials said no interagency meetings have been held nor any scheduled to discuss the option.

But Bush's comment appeared to be more than an off-the-cuff remark because White House press secretary Scott McClellan used almost identical language in response to the same question at his briefing. "We're always looking at all our alternatives when it comes to dealing with these detainees," McClellan said.

With about 540 prisoners being held at Guantanamo Bay, the government relies on the base as its main detention facility for suspected terrorists, but has been rocked by allegations of abuse and complaints that prisoners have been held in some cases for years without charges or publicly known evidence. Amnesty International recently termed it the "gulag of our time." A Defense Department investigation found several instances of mistreatment of the Koran.

Sen. Joseph R. Biden Jr. (Del.), ranking Democrat on the Foreign Relations Committee, on Sunday called for the Guantanamo Bay camp to be shut down; former president Jimmy Carter seconded the idea Tuesday.

In the interview, Bush again rejected the Amnesty International characterization and said allegations of misconduct have been investigated. "I will tell you that we treat these prisoners in accordance with international standards," he said. "And that's what the American people expect."

The president reiterated the need to hold many of the detainees there to continue interrogating them for intelligence about international terrorist organizations. "It's in our nation's interest that we learn a lot about those people that are still in detention because we're still trying to find out how to better protect our country," he said.

On other topics, Bush again urged China to "keep the pressure on" North Korea to return to six-party talks aimed at persuading Pyongyang to abandon its nuclear weapons program. He said seeking United Nations sanctions is an option: "It's on the table."

Bush said the United States has "a complex relationship" with China but added that he trusts the leadership in Beijing. "So far I do," he said. "We'll see."

Shrugging off bad poll numbers, Bush said he could not "live with myself" if he did not take on big issues such as Social Security.

Bush seemed amused by the suggestion by Lynne V. Cheney, wife of the vice president, that Laura Bush could run to succeed him in 2008. The president attributed it to his wife's widely praised comedy routine at the White House correspondents dinner recently. "I don't think she's going to run for office," he said. "It's an unusual city here where she gets a couple of good cracks off on her husband at one of these events, and then all of a sudden they've got her running for president."

Staff writer Jim VandeHei contributed to this report.