Sat Sep 29, 12:16 AM ET

YANGON - A special United Nations envoy is due in Myanmar Saturday after a crackdown on protesters, with the US calling on the ruling junta to allow him to meet with democracy leader Aung San Suu Kyi.

UN chief Ban Ki-moon has dispatched Ibrahim Gambari to broker talks between the military and its pro-democracy opponents, who have mounted two weeks of mass nationwide rallies.

Members of the protest movement vowed to come out on the streets again Saturday, despite a three-day offensive by security forces that has left at least 13 dead and hundreds more jailed.

"We are ready to go to town again. We will start it all over again and we are very hopeful that things will become much more intense as the hours go by," one pro-democracy campaigner involved in the protests told AFP.

"I expect quite a lot of people to be on the streets again today also," he said.

US President George W. Bush and British Prime Minister Gordon Brown on Friday led international condemnation of the violence, and renewed pleas to the Myanmar junta to make a "peaceful transition to democracy".

Gambari's itinerary has not been released, but on previous visits he has met with regime leader Senior General Than Shwe, and once with Aung San Suu Kyi, who has been under house arrest for most of the past 18 years.

"We have called on the Burmese to allow him to be able to meet with anyone he wants to meet -- the military leaders, the religious leaders and Aung San Suu Kyi," White House spokeswoman Dana Perino said Friday.

Myanmar's main city of Yangon, the focus of the protests which represent the strongest challenge to military rule in nearly two decades, was under extremely tight security on Saturday morning, with troops numbers visibly higher.

The two Yangon-based army divisions which have spearheaded the crackdown have now been joined by 66 Division from Pago which lies northeast of the city.

The former capital's main pagodas, which have been rallying points for the protests, remained off-limits and 20 military trucks were stationed at Sule Pagoda in downtown Yangon.

Only a few people ventured onto the streets, marketplaces were closed, and a handful of private cars and taxis were on the roads.

The only people in sight were some householders rushing to buy essential food items before trouble breaks out again.

"We try to finish everything we need to do, buying food and so on, before 11. After that we will not go outside," said one man.

The Buddhist monks who initially led the protests, turning out on the streets in their thousands, were nowhere to be seen after a brutal campaign of arrests, bashings and monastery raids which has shocked the country.

Troops have blockaded many big monasteries, including those in the religious capital of Mandalay in central Myanmar, and monks are only allowed to move around in small groups.

A Western diplomat based in Yangon said Saturday there were reports of divisions within the military on how to handle the crisis in Mandalay, home to the majority of Myanmar's 400,000 monks.

In the past there have been regular reports of tensions at the highest levels of the junta, particularly between Than Shwe and the regime's number-two Maung Aye.

On Friday, diplomats said they had received information from several sources about "acts of insubordination" within the army and that some soldiers were willing to take the side of demonstrators.

The diplomats also said the suffocating security presence had succeeded in reducing the intensity of the protests Friday, when only about 10,000 turned out in Yangon compared to tens of thousands in the previous days.

In Mandalay, thousands of young people on motorbikes rode down a major thoroughfare towards a blockade set up by security forces who unleashed a volley that witnesses believed could have been rubber bullets.

Global pressure on the Myanmar regime has mounted in recent days as images of gunfire, baton charges and tear gas used against demonstrators has galvanised world opinion.

The State Department announced more than three dozen additional government and military officials and their families would be barred from traveling to the United States.

Public protesters have shown their anger outside Myanmar embassies across the globe. The UN Human Rights Council called a special meeting on the Myanmar unrest for Tuesday in Geneva.

Myanmar's main Internet connection was cut Friday, severely reducing the flow of video, photos and first-hand reports of the violence which helped inform the world of the crisis in the isolated nation.