By Alphonso Toweh

MONROVIA, Dec 11 (Reuters) - Liberian police fired teargas to disburse supporters of George Weah who rampaged through a Monrovia suburb after the soccer millionaire told a rally he had been cheated in November's presidential run-off election.

Weah and his Congress for Democratic Change party say the Nov. 8 election, won by former Finance Minister Ellen Johnson-Sirleaf, was rigged and have filed a complaint with the National Elections Commission.

Riot police with batons and plastic shields surrounded Weah's party headquarters after more than a thousand of his young supporters blocked traffic, smashed car windscreens and pelted officers with rocks in the street outside the compound.

"No George Weah, no Liberia!" chanted the demonstrators, some of them stripped to the waist. Large traffic jams formed on the highway outside Weah's party offices, one of the main routes into central Monrovia.

Police Commissioner Joseph Kerkulah told Reuters: "What we are doing now is to protect lives and property, so we have deployed riot police to ensure the free flow of traffic."

Several arrests were made as police attempted to clear protesters from the street.

"We were celebrating the return of our standard bearer, George Weah. After his speech we began to jubilate and the police came and beat us with batons," said Weah supporter Edith Thompson. "The first law of nature is self preservation so we decided to protect ourselves."

Johnson-Sirleaf, known as the "Iron Lady", won the run-off with almost 60 percent of valid votes versus Weah's 40, becoming Africa's first elected female president.

She is in the United States on a nine-day visit where she plans to meet officials from the World Bank and the International Monetary Fund, and U.S. Secretary of State Condoleezza Rice.

Liberia's first elections since a brutal 14-year civil war ended in 2003 were meant to make an end to violence and return Africa's oldest republic, founded by freed slaves in 1847, to prosperity.