BAGHDAD — Sen. John McCain, the likely Republican presidential nominee who has linked his political future to U.S. success in Iraq, was in Baghdad on Sunday for meetings with Iraqi and U.S. diplomatic and military officials, a U.S. government official said.

Details of McCain's visit, which had been anticipated, were not being released for security reasons, the U.S. Embassy said. It was unclear who he met with; no media opportunities or news conferences were planned.

McCain, a strong supporter of the U.S. military mission in Iraq, is believed to be staying in the country for about 24 hours.

"Senator McCain is in Iraq and will be meeting with Iraqi and U.S. officials," said Mirembe Nantongo, spokesman for the U.S. Embassy in Baghdad.

This is the senator's eighth visit to Iraq. He's accompanied by Connecticut Sen. Joe Lieberman, an independent, and Sen. Lindsey Graham, R-S.C. Before leaving, McCain said the trip to the Middle East and Europe was a fact-finding venture, not a campaign photo opportunity.

The senator last met with Iraqi Prime Minister Nouri al-Maliki during the Thanksgiving holiday.

"We were informed that John McCain landed in Iraq Sunday morning. A meeting will take place with the Iraqi government," said Ali al-Moussawi, an official in the prime minister's office.

McCain was to meet Sunday with Deputy Prime Minister Barham Saleh. Later in the day, he and Gen. David Petraeus, the top U.S. commander in Iraq, were to talk. It also was thought McCain would meet with al-Maliki.

McCain's weeklong trip also includes stops in Israel, Jordan, Britain and France.

He is expected to meet with British Prime Minister Gordon Brown for the first time, and French President Nicolas Sarkozy for the third time. He met and corresponded with Sarkozy both before and after the French president was elected. They last saw each other last summer.

McCain has relationships with every leader in Israel he plans to see, including Prime Minister Ehud Olmert, Foreign Minister Tzipi Livni, Defense Minister Ehud Barak and hawkish opposition leader Benjamin Netanyahu.

McCain told U.S. reporters last week that he would be visiting Iraq, and expressed worries that insurgents might try to influence the November presidential election with increased attacks in Iraq.

"Yes, I worry about it," he said Friday in Springfield, Pa. "And I know they pay attention, because of the intercepts we have of their communications."

McCain told reporters later that al-Qaida remains smart and adaptable despite an increase of U.S. troops in Iraq.

A defiant supporter of the 2003 invasion and President Bush's troop increase last year, McCain is likely to focus in Iraq on the drop in sectarian violence and U.S. and civilian casualties since last summer.