Iraqi forces were on the eastern edge of Islamic State-held Mosul on Tuesday, encountering snipers, landmines and road-blocking boulders, a report said.

Troops came within hundreds of meters of Mosul on Monday evening and are now the closest they've been since launching an operation two weeks ago to reclaim the city from more than two years of Islamic State (IS) rule, the CNN report added.

Experts and officials have said that entering Mosul will likely trigger the fiercest fighting seen yet in the offensive and that the battle is expected to be fought street to street or even house to house.

The plan is to squeeze IS fighters from different directions, commanders say.

But reports that the militant group has brought thousands of civilians -- mostly women and children -- into Mosul as human shields raises serious concerns that there could be a high number of civilian casualties in the battle, CNN said.