YANGON, Myanmar — Nearly 1,000 Buddhist monks, joined by thousands of their countrymen, marched in Myanmar’s largest city Thursday in the biggest challenge in at least a decade to the iron-fisted junta, a show of strength rare under military rule.

Authorities normally quick to crack down hard on dissent left the marchers alone, apparently wary of stirring up further problems. The monks said they would march again next week.

Processions of monks converged from various monasteries around Yangon in the early afternoon at the golden hilltop Shwedagon pagoda, the country’s most revered shrine. They prayed there before embarking on a more than three-hour march through Yangon in steady rain, gathering supporters as they went.

Monks at the head of the procession carried religious flags and an upside-down alms bowl, a symbol of protest.

Some monks are refusing alms from the military and their families — a religious boycott deeply embarrassing to the junta. In the Myanmar language, the term for “boycott” comes from the words for holding an alms bowl upside down.

As the monks marched calmly through the streets, some onlookers offered refreshments while others kept the streets clean by picking up water bottles.

The government appeared to be handling the situation gingerly, aware that any action seen as mistreating the monks could ignite public outrage. They are aware that restraining monks poses a dilemma, because monks are highly respected in predominantly Buddhist Myanmar, and abusing them in any manner could cause public outrage.

A member of one of the junta’s neighborhood councils said it had been given instructions by authorities not to interfere with the protesting monks.

“We’ve been instructed to be patient and to even protect the monks,” said the official.

No uniformed security personnel were in sight, although dozens in plainclothes stood by without interfering. Car and motorbikes carrying junta supporters — present at most previous protests — were also absent.

Witnesses said the number of marchers swelled to as many as 5,000 by the end, many of them linking arms in a human chain to protect the monks from outside agitators.

It was the third straight day that monks have marched in Yangon. Their activities have given new life to a protest movement that began a month ago after a huge government-ordered increase in fuel prices.

The protests express long pent-up opposition to the repressive regime and have become the most sustained challenge to the junta since a wave of student demonstrations that were forcibly suppressed in December 1996.

As the monks marched, they chanted sermons, avoiding explicit anti-government gestures. But their message of protest was unmistakable to fellow citizens as monks normally leave their monasteries only for morning rounds with bowls seeking alms.