(Updates with U.S. embassy comment, background)

BAGHDAD, Feb 23 (Reuters) - A barrage of mortar bombs or rockets hit Baghdad's heavily protected Green Zone, home to the U.S. embassy and Iraqi government ministries, on Saturday, but there were no immediate reports of casualties or damage.

A siren wailed in the Green Zone warning people to take cover amid a series of at least 10 explosions, Reuters reporters said.

"I can confirm that we did receive indirect fire and that it was multiple rounds," said U.S. military spokesman Major Brad Leighton, referring further queries to the U.S. embassy.

U.S. embassy spokeswoman Mirembe Nantongo refused to say whether there had been casualties or damaged.

"To maintain operational security, we do not comment on indirect fire into the International Zone," she said.

The 10 sq km (4 sq mile) Green Zone, located on the left bank of the Tigris River that cuts through Baghdad, has often been targeted by mortars and rockets, although attacks have declined as security has improved in the capital.

The U.S. military has blamed missile attacks on the Green Zone on so-called "special groups", rogue elements of Moqtada al-Sadr's Mehdi Army militia they say receives funding and weapons from neighbouring Iran. Iran denies the charge.

On Friday, Sadr renewed a six-month ceasefire which he first called in August to reorganise his splintered militia. The U.S. military welcomed the extension but said it would continue to hunt down the rogue units. (Reporting by Ross Colvin; Editing by Michael Winfrey)

AlertNet news is provided by