British forces started withdrawing from the Joint Coordination Centre in central Basra as part of a plan to hand the facility over to Iraqi security forces, it was reported on Sunday.
British troops are expected to remain in the former presidential palaces and continue cooperation with their Iraqi counterparts.
"The withdrawn troops moved to the British base at Basra International Airport in the north-west of the city," a media spokesman from the multinational forces in southern Iraq, Major Matthew Bird, told the independent news agency Voices of Iraq.
Bird denied that a complete pullout from Basra is due but said the British forces will eventually hand over to Iraqi forces its bases in the presidential palaces and the joint coordination centre in the heart of the city.
The British forces reportedly withdrew a total of 1,600 soldiers from Basra, 550 km south of Baghdad, during the past few months.
Meanwhile, Arab broadcasters were reporting a security surge in and around Baghdad.
According to al-Arabiya, a curfew on vehicles came into effect early Sunday in Baghdad and surrounding cities, in addition to the holy Shia city of Karbala to protect thousands of Shia visitors flocking from Baghdad to Karbala for a festival.
The commemoration of "al-Ziyara al-Shaabaniya", which comes ahead of the Muslim holy month of Ramadan, takes place on Wednesday and marks the anniversary of the birth of iconic Shia figure al-Imam al-Mahdi, generally seen by Shia as a Christ-like "saviour".