Hundreds of people demonstrated Wednesday against the government's sharp fuel price increase for the second time in a week, undaunted by the arrest of at least 13 top pro-democracy activists.

About 300 protesters walked from the northern outskirts of the commercial capital Yangon, encouraging onlookers to join their display of opposition to the military regime, witnesses said on condition of anonymity, citing fears of reprisals.

The government had arrested the opposition leaders on Tuesday, facing the prospect of growing public protests of the price increase.

"Though our leaders had been arrested, we will continue with our movement. We will not fear any arrest or threat," said Mie Mie, a member of the dissident 88 Generation Students group. His comments came during the march, which was watched by plainclothes police officers.

The protesters cut short their march and dispersed after unidentified junta supporters attacked several demonstrators with heavy sticks and took at least eight away in cars, according to the witnesses.

One of the eight, Naw Ohn Hla, said they were taken to a state security office, accused of agitating the crowd, and held for several hours for questioning before being released.

State media reported earlier that 13 leaders of the 88 Generation group had been detained Tuesday night. The official New Light of Myanmar newspaper said "agitators" were arrested for trying to undermine the "stability and security of the nation" and could face up to 20 years in prison.

Those arrested included Min Ko Naing and Ko Ko Gyi, two of the country's most prominent activists, the newspaper said. Min Ko Naing spent 16 years in prison despite international calls for his release and numerous awards for his nonviolent calls for democracy in Myanmar.

On Monday, the 88 Generation led more than 400 people in a protest march through Yangon against the doubling of gasoline prices to $1.94 a gallon on Aug. 15. The hike immediately affected commuters as bus fares increased along with the price of basic consumer products. The government holds a monopoly on fuel sales and subsidizes them.

"We are marching to highlight the economic hardship that Myanmar people are facing now, which has been exacerbated by the fuel price hike," a protester who identified herself only as Mimi told onlookers Wednesday.

A planned afternoon protest in a busy downtown area near Sule Pagoda was stymied when plainclothes security personnel seized at least three activists and hustled them away in buses. Some of those arrested had been carrying placards.

Myanmar's military leaders have been widely criticized for human rights violations, including the 11-year house arrest of Nobel Peace laureate Aung San Suu Kyi. The country has been under military control since 1962.

Those who broke up the morning protest could not immediately be identified. But it has become a common tactic for the government to use members of the Union Solidarity and Development Association -- USDA -- to assault and intimidate the junta's opponents.

A Washington-based activist group, the U.S. Campaign for Burma, said in a statement that five university students and three members of another activist group were also arrested in separate sweeps by the authorities. State media did not mention those arrests.

Members of the 88 Generation Students were at the forefront of the 1988 pro-democracy uprising -- preceded by protests of rising rice prices and other economic hardships -- and were given long prison terms after the rebellion was brutally suppressed by the military.

They have been spearheading recent protests with petition campaigns, prayer vigils and other actions to free political prisoners and promote a return to democracy.