Some 1,100 Afghan police officers were deployed in Marjah Wednesday, as the national flag was hoisted in the key Taliban stronghold amid a US-led assault, an interior ministry spokesman said.

"We have 1,100 extra police. It is a force to take over after the military operations in both districts," of Marjah and the district of Nad Ali, spokesman Zemerai Bashari in Kabul told reporters at the NATO HQ in Brussels via video link.

The plan is to eventually have 1,600 "trained and equipped" police deployed in the key area, he added.

The raising of the flag was a symbolic move after slow progress in what officials bill as the biggest operation in Afghanistan since the 2001 US-led invasion toppled the Taliban government and flung the United States into a costly eight-year war.

Marjah is also part a big drugs production area in the southern Helmand province.

In Marjah we did not have police forces," the spokesman said, underlining the difficulties of the US-led surge to tame the region.

Since Saturday some 15,000 Afghan, US and NATO troops have been waging the offensive and have reportedly run into stiff resistance from Taliban firing behind human shields and mining roads, buildings and trees with bombs.