Coalition commanders fighting for control of Basra say a “popular uprising” is underway inside the southern Iraqi city, a reporter for the Sky News TV channel said on Tuesday in a live broadcast from the west of the city.

He said the uprising — details of which were not given — might have triggered a decision by coalition forces to make “a big push” for the city, using heavy artillery.

Earlier Tuesday, spokesmen for coalition forces in the Gulf said their troops faced the prospect of street fighting in Basra after meeting fierce resistance on the outskirts.

Relief agencies meanwhile warned of a humanitarian crisis in the metropolis.

Military planners had expected little resistance in the city, pinning their hopes on the Shiite Muslim majority who have long been repressed by President Saddam Hussein’s mainly Sunni regime.

The British army is reported to have three brigades to the south and west of Basra, where an estimated 1,000 so-called Iraqi “irregulars” were resisting the coalition advance.

Sky News is owned by the Australian-US media magnate Rupert Murdoch, who has expressed strong support for the US-led war in Iraq.