BAGHDAD – British troops handed over their last base inside the southern city of Basra on Wednesday, leaving it to local Shiite Muslim political parties and militias whose power struggles often have spilled over into violence.

The British troops, who withdrew to an airport outside the city, were hoping their exit from Iraq’s second-largest city would let Iraqi authorities take charge and resolve simmering conflicts. But Iraqi civilians and analysts warned that Basra had become a symbol of Shiite infighting and corruption centered on the region’s lucrative oil fields, which account for the majority of Iraq’s estimated 1.5 million barrels of oil exported daily.

Iraqi Prime Minister Nouri al-Maliki, a Shiite, has struggled to bring the area under control since he became premier last year. Al-Maliki officially fired the region’s governor, Mohammed Waeli, after the regional council voted to dismiss him earlier this summer amid charges that he was involved in corruption, including oil smuggling. But Waeli has defied the order and remained in power.

The 550 British soldiers moved out of the one-time residence of former dictator Saddam Hussein on Monday, but the keys to the palace were handed over Wednesday. The British vacated two other main bases in the city this year.

“Having a foreign army on the streets is not going to be part of the end stage here; the nationalist feeling is strong here, and people do not tolerate foreigners too kindly,” said British military spokesman Maj. Mike Shearer.

Army Lt. Gen. Raymond T. Odierno, the day-to-day commander of U.S. troops in Iraq, told reporters Tuesday that the British move was a “solid plan.” But a war of words has erupted away from the battlefield, between former British and U.S. military officials. Retired U.S. Gen. Jack Keane, who advised the Pentagon on Iraq earlier this year, has criticized the British performance in Basra. In turn, the former head of the British army, retired Gen. Mike Jackson, has derided the U.S. policy in Iraq as bankrupt.

Al-Maliki congratulated Iraqis for taking full control of the city and urged them to “hold on to national unity and to seek the country’s high interests rather than the narrow group and political interests.”

Iraqi national security adviser Muwafaq al-Rubaie, who attended the hand-over of the palace, urged Basra residents to keep the peace. “I am calling on the people of Basra to cooperate and leave (behind) the division and conflict,” he said.

Al-Maliki dispatched two strongmen to Basra to bring order to the city: Gen. Mohan al-Freiji, who is described by some Western officials as having possible links with the Badr Corps militia, has been put in charge of Basra’s security plan; Gen. Jalil Khalaf, a confidant of Iraq’s defense minister, is to lead the police corps.