LONDON — The tactical redeployment of 500 British troops from Saddam Hussein’s old palace in the center of Basra to the more secure and better-protected compound at the city’s airport is an important milestone toward Britain’s ultimate objective of returning the city to Iraqi control.

When British troops moved into southern Iraq following Saddam’s overthrow in the spring of 2003, they were given responsibility for administering four of Iraq’s eighteen provinces.

Three of them have now been handed back to the Iraqis, and the fourth — Basra — could be returned as soon as the end of this year, assuming that the Iraqi security forces are up to the job of maintaining some semblance of law and order.

By making the decision to withdraw the British army’s last remaining battle group from Basra’s city center, coalition commanders have concluded that local Iraqi forces, which have undergone intensive training by British specialists, are now in a position to take control of the city center.

But whether they will be able to control the lawless militias and criminal gangs — some of which are financed and trained by Iran — that are vying for control of the city is another matter.

The Iraqis have suffered mixed fortunes since they assumed control of the three other provinces during the past year.

Last month the governors of Muthanna and Qadasiyah, two of the provinces recently returned to Iraqi control, were killed in roadside bomb attacks, victims of the intense rivalry between Shiite militias for control of southern Iraq when coalition forces withdraw.

The fighting between the militias has prompted some of President Bush’s key military advisers in Washington to claim that British forces in Basra have already surrendered control of the city to militant groups, a claim that has been rigorously denied by British commanders.

They point out that the level of basic supplies such as water and electricity are better in southern Iraq than in many other parts of the country, mainly thanks to the efforts of the Royal Engineers who have so far succeeded in restoring 24-hour electricity to half the city’s two million population.

But however much the military may point to the positive aspects of the British deployment, the fact remains that there has been a radical change in the attitude of the local population toward Britain’s continuing military presence in the area.

An army that was once welcomed as liberators of an oppressed people from Saddam’s tyranny is now regarded as an army of occupation.

The days when soldiers could undertake foot patrols wearing soft hats — as the British did in Basra immediately after Saddam’s demise — are long gone. Nowadays, when British troops venture out from their compounds, they do so in heavily fortified convoys to protect themselves from the murderous attentions of local militias.

The big change in the operational atmosphere over the past two years has also resulted in a dramatic increase in the number of British fatalities.

The number of British soldiers killed in Iraq so far this year already outnumbering the total killed during the invasion four years ago. So far a total of 168 British lives have been lost in the four-and-a-half years since the invasion, the most recent in a roadside bomb attack last month.

By withdrawing the main bulk of the fighting troops to the airport, some five miles outside the city, the British government is no doubt hoping that it can keep future casualties to an absolute minimum.

But suggestions that the handover of Basra to Iraqi control will enable Britain to undertake a complete withdrawal of its troops next year are overly optimistic. The 5,500 troops now based at Basra airport will still be used to support the Iraqi security forces in their attempts to control local insurgent groups. And even if the Iraqis prove themselves capable of imposing order, the British government’s long-term commitment to supporting Iraq’s transition from dictatorship to democracy means that British troops are likely to remain in Basra for years rather than months.