Sen. John McCain arrived in Baghdad on Sunday for an unexpected visit with Iraqi and US diplomatic and military officials, a US government official said. The details of McCain's visit were not being released for security reasons, the embassy said. "Senator McCain is in Iraq and will be meeting with Iraqi and US officials," said Mirembe Nantongo, spokeswoman for the US Embassy in Baghdad. The timing of the visit by the soon to be Republican presidential nominee was not announced and he was believed to have been in the country for several hours before reporters were able to confirm his presence. There were no media opportunities or news conferences planned for the visit. McCain, who is believed to be staying in Iraq for about 24 hours, is on his eighth trip to Iraq. The senator met with Iraq Prime Minister Nouri al-Maliki last November during the US Thanksgiving holiday, and he is accompanied on the trip by Sens. Joe Lieberman of Connecticut and Lindsey Graham of South Carolina. Ahead of the trip, McCain reportedly insisted that the visit was a fact-finding venture, not a campaign photo opportunity. McCain was meeting with Iraqi Deputy Prime Minister Barham Saleh. Later in the day, he and Gen. David Petraeus, the top commander in Iraq, were planning to meet. "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 Iraqi prime minister's office. There were no details immediately available about McCain's meetings and his schedule for the day apparently remained in flux, a US official said on condition of anonymity as they were not authorized to release the information. McCain's weeklong trip also includes stops in Israel, Britain and France - all countries where he has made many visits in the past. McCain is expected to meet with British Prime Minister Gordon Brown for the first time, and for a third time with French President Nicolas Sarkozy for the third time, whom he met and corresponded with both before and after he was elected. The two last saw each other over the 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. Ahead of the trip, McCain expressed worries that insurgents might try to influence the November general election with increased attacks in Iraq. "Yes, I worry about it," he said Friday in Springfield, Pennsylvania. "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 US troops in Iraq. "We have had great success with the surge, but to think they're not capable of orchestrating really strong attacks ... I think is an underestimation of the enemy," McCain said. "We still have the most lethal explosive devices coming across the border from Iran into Iraq," he said. "We still have suicide bombers landing at the airport in Damascus and coming into Iraq as we speak. "So I would not be surprised if they make an attempt. I believe that we can counter most of it, as we are countering. But there will still be spikes and difficulties and challenges associated with this conflict. Otherwise, I'd be advocating that they come home," he said. A defiant supporter of the 2003 invasion and President George W. Bush's troop increase last year, McCain is likely to focus in Iraq on the drop in sectarian violence and US and civilian casualties since last summer.