Kufa (AsiaNews/Agencies) – Mortar attacks against a mosque in Kufa killed 27 and injured 63. The mosque was packed with people getting ready to go to Najaf to greet the return of Grand Ayatollah Ali al-Sistani.

Al-Sistani, who is the prime marja or Shiite spiritual reference in Iraq and the world, came home yesterday deciding to march to Najaf to end peacefully the violent stand-off that has been raging in the city for the past three weeks.

A few hours later snipers opened fire against a crowd of thousands of people marching from Kufa to Najaf killing at least one person. It was unclear who fired the shots.

Hussam al-Husseini, a spokesman for radical Shiite Moqtada al-Sadr accused the Americans, but the US army denied any involvement.

"In the last 48 hours we have not conducted any military operations in Kufa," said marine spokeswoman Carrie Carrie Batson. She added that in the last few weeks al-Sadr's militants were responsible for "indiscriminate fire" that injured many civilians.

For several weeks the Moqtada al-Sadr's Mahdi army has been holed up inside the Imam Ali Shrine in Najaf trying to stir up a revolt against the presence of foreign troops in the country and the new Iraqi government.

The government of Prime Minister Iyad Allawi has called on Moqtada al-Sadr to disband the Mahdi army and surrender its weapons in exchange for which he would be allowed to take part in the emerging political process. Al-Sadr has always refused.

The young rebel Shiite leader is unpopular in many quarters within the Shiite community and the wider Iraqi population. Al-Sistani's return and the march on Najaf could further isolate him in the Shiite community.

Grand Ayatollah al-Sistani flew back from London via Kuwait yesterday after receiving medical treatment in the UK for heart problems. Upon his arrival he called on his followers to march on Najaf from every part of Iraq. This morning he left Basrah in a convoy of cars and buses for the 400 km long trip.

Al-Sistani aims to turn the cities of Najaf and Kufa into demilitarised zones demanding that al-Sadr's militants disarm and leave the Imam Ali Shrine.  At the same time, he is demanding that US troops end the encirclement of the sanctuary and leave law and order enforcement to Iraqi police.