Najaf (Iraq), May 6 (Reuters): US troops attacked Shia militia forces around the Iraqi holy city of Najaf today, seizing the local governor’s offices and killing 41 fighters, a senior official in the US occupation authority said.

In what seemed a broad move against insurgents across southern Iraq, US tanks moved unopposed into the centre of the nearby holy city of Kerbala, destroying offices used by the Mehdi Army militia of Shia cleric Moqtada al-Sadr.

Eyewitnesses reported fierce battles in and around Najaf and the nearby town of Kufa. One saw US tanks at the governor’s building on Najaf’s main street. It was the boldest action yet against an insurgency launched a month ago by Sadr. Aged about 30 and with a following among mainly young Shias, the cleric demanded Americans leave Iraq.

But rival Shia leaders have been increasingly critical of his stationing of thousands of fighters in the sacred city. He is wanted over the murder of another cleric in Najaf last year.

In Kerbala, residents saw US tanks blast away Sadr’s offices with heavy machinegun fire before taking up positions in the centre, about 500 metres from the main shrines. Italian forces said they fought Mehdi Army fighters south of Nassiriya, another Shia town.

Thousands of US-led troops have been encircling Najaf and have fought Sadr’s men elsewhere in recent days in the south.

Today, Paul Bremer, the US administrator of Iraq, appointed a new governor for Najaf and denounced Sadr.

Plumes of smoke rose from one area as US helicopters swooped low overhead in Najaf. US forces have said they will refrain from entering shrines or offending religious sentiment.