Afghan interim leader Hamid Karzai has reiterated pleas for more foreign security forces in Afghanistan after his handpicked governor in an eastern province was routed in heavy tribal fighting.

Karzai urged a wider role for international peacekeeping troops during talks in London but Prime Minister Tony Blair said Britain's military involvement had limits.

While assuring Karzai there would be a "long-term" international commitment, Blair did not promise to extend Britain's presence in Afghanistan, where bloody tribal infighting erupted this week.

Karzai's choice for governor of eastern Paktia province, Pashtun tribal chief Padsha Khan, was forced into a humiliating retreat Thursday after two days of heavy fighting against rival warlord Saif Ullah.

The clashes around Gardez, 100

km south of Kabul, left around 50 people dead and highlighted the frailty of the UN-backed interim government set up following the collapse of the Taliban regime in December.

The fighting started Wednesday when Ullah, who took control of the local tribal council after the Taliban evacuated, ordered his men to open fire as Khan's forces tried to raise the new national flag over the governor's mansion.

US warplanes circled above the rundown town of about 50,000 people and according to local Afghan garrison commander and Khan loyalist Ghalam Mehidi, US special forces were nearby watching the battle.

The town remained tense throughout Friday night following the retreat from Khan's troops from the surrounding hilltops. Khan himself appeared furious at his commanders and has not conceded defeat.

Ullah is loyal to pre-Taliban president Burhanuddin Rabbani, the figurehead of the Northern Alliance which helped oust the Taliban from power, and Khan is loyal to Karzai's royalist faction and ex-king Mohammed Zahir Shah.

Interim Afghan Foreign Minister Abdullah Abdullah, speaking to reporters in New York Thursday, described the battle as "a single unfortunate incident".

But he conceded it was a telling illustration of the problems facing Afghanistan as it struggles to emerge from 23 years of foreign invasion and civil war, with "at least" 700,000 people still bearing arms.

"The interim government should interfere in that issue and solve it," he told a news conference on the sidelines of the World Economic Forum, though disarming warlords was "an issue that has to be dealt with in a process -- it is not just a decision for today or tomorrow."