Fri Sep 28, 4:28 PM ET

WASHINGTON - US President George W. Bush and Prime Minister Gordon Brown Friday renewed pleas to the Myanmar junta to end a crackdown on pro-democracy protestors which has left at least 13 dead.

The two men discussed the situation in Myanmar and "the need for countries around the world to continue to make their views clear to the junta, that they need to refrain from violence and move to a peaceful transition to democracy," White House spokesman Scott Stanzel said.

"What is going on is certainly very troubling, and we call on the junta to stop the violence against people who want to bring about, peacefully, democracy," Stanzel added.

Ignoring world pressure, security forces on Friday clamped down on protests in Myanmar's two biggest cities, firing warning shots and using baton charges in the third day of the crackdown.

The military regime also appeared to have cut the main Internet link to block images and reports of the violence from the isolated nation, which have galvanized world opinion against the ruling generals.

"The reports today that the junta has tried to cut off access to the Internet in that country are very telling. They don't want the world to see what is going on there," said Stanzel.

"They don't want the pressure that the world community is bringing to bear."

Brown and Bush also stressed the importance of a visit to Myanmar this weekend by the UN special envoy Ibrahim Gambari during a secured video conference, Stanzel said.

The White House has called for Gambari to be allowed to visit democracy leader Aung San Suu Kyi who is under house arrest in Yangon, during his trip to the country due at the weekend.

"We are very pleased that UN envoy Mr Gambari is going to be going to Burma, he will be there tomorrow," said White House spokeswoman Dana Perino, using the former name for Myanmar.

"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," she added.

On Friday about 10,000 people surged onto the streets of the main city of Yangon, playing a deadly game of cat-and-mouse as they repeatedly confronted police and soldiers before scattering and regrouping once more.

In the central city of 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.

The US administration has slapped economic sanctions on 14 leaders of the military junta, including its leader general Than Shwe, and Bush has called on Myanmar's powerful neighbor, China, to use its influence on the regime to end the violence.