Linking arms for mutual support, grim in the face of plainclothes paramilitary gangs, small groups of protesters in Myanmar have staged street demonstrations for nearly two weeks in the most sustained defiance of the country’s ruling junta in a decade.

The protests have dwindled in size since they began on Aug. 19, but to the surprise of outside analysts, they have continued to erupt in several parts of the country. They do not appear to be centrally organized and have continued despite the arrests of a number of antigovernment leaders.

“A week and a half ago, people were saying the protests didn’t have that much future,” said Dave Mathieson, an expert on Myanmar with Human Rights Watch in Thailand. “But they are starting to spread, and they are continuing in Rangoon.”

Rangoon, now known as Yangon, is the commercial capital of Myanmar, formerly known as Burma.

The authorities are hunting down opposition figures, raiding their homes, distributing photographs of them and reportedly telling hotels to notify officials of their presence. The main opposition party told Reuters that at least 100 people had been arrested in the past week.

In Washington, President Bush called on Myanmar to “stop its intimidation” of demonstrators, saying, “I strongly condemn the ongoing actions of the Burmese regime in arresting, harassing and assaulting pro-democracy activists for organizing or participating in peaceful demonstrations.” The persistence of the demonstrations reflects deep unhappiness with economic hardships and strong-arm government rule in one of the most repressive nations in Asia, analysts said.

A sharp rise in prices for fuel and cooking gas on Aug. 15, without warning or explanation, provided a focus for the protests. They have continued even though the government has pressed bus operators to lower prices.

Exiles and human rights groups in Thailand have received reports of a number of other protests in recent days, including demonstrations in the central town of Meikhtila and in Sittwe, the capital of Rakhine State in western Myanmar.

The unrest could complicate the government’s plans to complete a constitutional convention and present a new charter to a popular vote. The carefully stage-managed convention excludes members of the opposition party of Daw Aung San Suu Kyi, the National League for Democracy, and has been dismissed by analysts both inside and outside the country as no more than a facade of a democratic process.

There have been unconfirmed reports that the convention will conclude Monday. According to the junta’s “road map to democracy,” next comes a “stable environment” in preparation for a referendum.

The protests may also be spreading because of transmissions through the Internet of photographs and video that have slipped past government controls. Some of the more arresting pictures show an outspoken critic of the ruling generals named Su Su Nway, 34, at the heart of a tiny group of demonstrators this week before she managed to slip away and evade arrest.

“I know they’ve been after me since our protest on Tuesday,” Ms. Su Su Nway told Reuters by telephone. “I heard they have sent pictures of three women activists, including me, to several of their offices.”

The visual images have given the small demonstrations a disproportionate impact, both abroad and at home.

“That’s the big difference from 1988,” said Mr. Mathieson of Human Rights Watch, referring to antigovernment demonstrations that swept the country then. “The technology is completely different. Even though the military’s power may be the same, the ability of the protesters to get their message around the country has grown.”

The 1988 demonstrations were crushed by the military, bringing the current junta to power. Thousands of people were killed.

In 1990, the junta held a parliamentary election and lost overwhelmingly to the National League for Democracy. The junta annulled the result, clung to power and began a fitful process of drawing up a constitution that it says will lead to a new round of elections.

Mrs. Aung San Suu Kyi, a Nobel Peace Prize winner, has been under house arrest for 11 of the past 17 years, and her release has been a primary demand of critics abroad.

Myanmar is mostly closed to foreign reporters, and the only news media to witness the demonstrations were local journalists for news agencies.

For now, the demonstrations are tiny compared with those of 1988, in part because the government has gone to great lengths to prevent a new uprising.

It has moved universities from major cities to disperse the students who have historically formed the core of protest. In addition, the creation of a new capital in a remote area has removed from Yangon the civil servants who swelled the protests in 1988.

The government has also stockpiled food in warehouses as a buffer against economic crises that could lead to unrest.

And it has created the civilian gangs that have beaten and arrested demonstrators this month. Wielding brooms and hoes, they pose as members of the public, chiding the demonstrators before beating and seizing them, according to wire service reports.

Known as the Swan-ar Shin, or Masters of Force, they appear to have taken the place of military intelligence enforcers in combating protests.

On Tuesday, according to the reports, they pushed their way through onlookers to rough up about 15 demonstrators before driving them away in trucks. On Wednesday, three trucks, each carrying about 20 young men, waited at the side of the road at Hledan Junction in Yangon, the scene of the biggest protests.