Thousands of followers of Muqtada al-Sadr, a prominent Shia leader, have protested in central Baghdad against a security pact with the United States.

The deal, which was signed by US and Iraqi officials earlier this week and is currently being debated by parliament, would allow US forces to stay in Iraq for another three years.

Demonstrators waved Iraqi flags and green Shia banners while chanting "No, no to the American agreement'' and "No, no to the agreement of humiliation" following Friday prayers.

The protest was held on Friday in Firdous Square, where US marines tore down a statue of Saddam Hussein during the US-led invasion in 2003.

Organisers placed an effigy of George Bush, the US president, holding a sign that said "the security agreement ... shame and humiliation" on a pedestal near a sculpture that replaced the Saddam statue.

After prayers were held, demonstrators pelted the effigy with plastic water bottles and sandles.

Security tight

Security was tight for the event, with heavily armed soldiers closing the area to traffic and army snipers on building overlooking the square.