WASHINGTON, June 6 (Reuters) - The U.S. Treasury on Wednesday warned Syria that more than 55 countries would seek to impose "maximum financial pressure" on President Bashar al-Assad's government in an effort to stop his regime's violence against Syrian people.

Addressing officials from Turkey, Japan and other countries, Treasury Secretary Timothy Geithner said he hoped that nations would soon join in taking appropriate actions against Assad's government including, if necessary, "Chapter 7" of the United Nations charter - a measure that could authorize the use of force.

Assad has so far defied a peace plan and ceasefire proposed by international envoy Kofi Annan and has continued to wage war against Syria's civilians.

"Absent meaningful compliance by the regime with the Annan plan, that is the direction in which we are soon headed," Geithner said at the Friends of Syria working group on sanctions, where officials from more than 55 countries gathered in Washington to discuss ways to beef up economic penalties against Assad's government.

The United States has imposed sanctions on Syria in an attempt to deprive Assad's government of resources needed to function and carry out its attacks. Qatar, which is co-chairing the working group with Turkey, has imposed similar penalties on Syria's financial institutions.

Geithner acknowledged that the sanctions would not be enough to stop the violence or bring about political change but said they played an important role.

"Strong sanctions make clear to the Syrian business community and other supporters of the regime that their future is bleak so long as the Assad regime remains in power," he said.