Around 200,000 people gathered in front of the United States embassy in the Indonesian capital in the biggest anti-war rally yet in the world's largest Muslim-populated nation.

The protestors gathered in the sprawling Monas square facing the US embassy, guarded by police wielding batons and shields.

Crowd estimates varied: the Central Jakarta police put the number at around 200,000, witnesses said 300,000 were present, while organisers claimed more than three million people showed up.

Thousands more were streaming into the venue from many directions as the organisers officially closed the rally at 11.00 am, about 60 minutes after it started.

The protestors marched past the well guarded US embassy on their way home. Many criss-crossed the city on their buses, cars and motorcycles, waving flags.

Among the public figures addressing the rally were the chairman of the National Assembly Amien Rais, one of his deputies, Andi Mappetahang Fatwa, and chairman of the Indonesian Council of Ulemas (MUI) Hamidan, who uses one name.

An older sister of President Megawati Sukarnoputri, Rachmawati, was also present as well as several religious leaders.

Two open trucks with huge loudspeakers, parked in front of the gate of the US embassy, were used as a makeshift stage for the speakers.

"Our message is very clear, the message of the Indonesian society is ... stop the war now," said MUI general secretary Dien Syamsuddin.

The rally organisers, the Indonesian Solidarity Committee for Iraqi People, said they expected about one million protesters to show up.

The organisers – a coalition of several Muslim organisations including the second largest Islamic movement, the Muhammadiyah, and the MUI which groups the nation's top clerics – dubbed the gathering a rally of "one million believers." Among the crowd were several Christian and Protestant youth groups, whose presence was acknowledged through public loudspeakers by the organisers.

Most of the participants were Muslims wearing white dress. Many carried the flag of the Justice Party, a small but vocal radical Muslim political group, as well as those of other political parties and organisations.

Police said around 600 personnel, including one company of about 100 women police, were present around the embassy and – because of the size of the protest – the road in front of the embassy was closed to traffic.

Members of the Muslim-oriented United Development Party for Reform carried a 100-meter (-yard) long light green piece of cloth, inscribed with the words "Stop the massacre in Iraq" to the site. People crowded around the banner to put their signatures on it.

The participants, many of them veiled mothers with their children, displayed anti-war posters and banners and yelled "Allah is Great". Others chanted religious verses.

"Stop the invasion of Iraq," "No war for Oil," and "Stop the slaughter of the people of Iraq," some of the posters read. Many urged the United Nations to be more assertive in its opposition to the war.

Organisers said they would also collect humanitarian aid for the Iraqi people.

Indonesia has seen daily protests against the US-led war on Iraq in most of its major cities.

Jakarta has strongly criticized the Iraq war and has been in the forefront of efforts to seek an emergency meeting of the United Nations Security Council or of the General Assembly in order to call a halt to the attack.