Protesters charged protective barriers guarding a meeting of some the world's top financial officials on Saturday and pelted police with stones and garbage bins, but were turned back by baton-wielding police and mounted officers.
About 3,000 people marched from a rallying point to the downtown hotel where the Group of 20 meeting of finance ministers and central bankers opened Saturday, and about 200 tried to break through a gap in a security barrier set up in a street outside the venue.
Police struck out with batons as they rushed to close the gap. Protesters through brown and red smoke grenades, shrouding the front line are in a pall. The clash was brief, and there were no apparent injuries.
At another place in the security cordon, masked protesters pelted police with small stones and threw large plastic garbage bins over barricades at police standing several yards away. The police stood their ground, and the protesters didn't break the cordon.
Energy security, climate change and the state of the global economy are on the agenda.
"I believe over the course of the weekend (if) we can come to a consensus and build agreement between countries that are represented here at this table then we will be advancing economic prosperity for all," Australian Treasurer Peter Costello, the meeting's chairman, said in opening remarks to the meeting.
Finance mandarins from 19 countries and the European Union, plus top officials of the World Bank and International Monetary Fund are at the talks. Formed in 1999, the G-20 includes the Group of Seven advanced industrial countries and the European Union as well as China, Brazil, India, Russia, South Korea and other major economies.
Argentina, Australia, Indonesia, Mexico, Saudi Arabia, South Africa and Turkey fill out the group, which altogether represents about 90 percent of the world's gross national product, 80 percent of the worlds' trade and two-thirds of its population.
"The discussions here today about trade, about energy and about macroeconomic circumstances proves very clearly that this is a very important fora," IMF Managing Director Rodrigo de Rato told reporters outside the meeting.
Security was tight. Chest-high metal fences have been erected around hotel venue. Hundreds of police, some in riot gear, have been deployed to keep protesters away. Commander have said they will allow protests, but no lawbreaking.
Protesters criticized the governments and institutions represented by the G-20 on a wide front, including the Iraq war, the environment and Western capitalist systems.
"We do not think that the poor and the environment will benefit from this meeting," said Ross Parry, 46, from a Christian activist group.
U2's Bono and Pearl Jam made surprise appearances at an activist-organized concert on Friday.
Reform of the IMF, rising interest rates, the Chinese and Japanese currency levels and efforts to economically isolate nuclear-armed North Korea are also likely to come up at the closed-door meetings.
Surging demand for oil and minerals from fast growing economies China and India have benefited commodity powers like Australia, while fanning concerns over the emergence of unstable supplies and market distortions.
De Rato told reporters Saturday that governments have no power to affect the value of major currencies and should leave that task to markets.
"The markets are the ones who fix the value of the most important currencies and governments won't be able to affect that," de Rato said.
Reforming the yuan
On Friday, U.S. Deputy Treasury Secretary Robert Kimmitt renewed Washington's call for China to move faster in reforming its currency, the yuan.
"We believe that the Chinese need to accelerate the movement of their exchange rate to reflect underlying market conditions," Kimmitt told reporters.
A group representing major international mining companies, the Energy and Minerals Business Council, is due to address G-20 delegates Saturday -- the first time a business group has had direct access to the forum.