Afghanistan's acting defense minister says reinforcements have been rushed to a besieged southern district threatened for days with takeover by Taliban fighters.

Masoom Stanekzai said on Wednesday fighting in the Sangin district of Helmand is continuing as army and police arrive to help security forces who have been pinned down for days.

He says Afghanistan's embattled security forces need international military help, especially air support, which would help reduce casualties.

Sangin is an important poppy-growing district in Helmand, which borders Pakistan and sits on transport routes for drugs, arms and other lucrative contraband.

Britain has sent a small contingent of soldiers to Helmand as advisers under the NATO mandate. The return of British troops is poignant, as they suffered more than 100 fatalities in Sangin during their 13-year combat mission.