Severe disruption to internet and cell phone services in Egypt was reported early on Friday as security forces braced for mass protests against the government.
Police in the eastern city of Suez fired tear gas as protesters threw stones and petrol bombs in the early hours of Friday. Seven people have been killed - five protesters and two policemen - and more than 100 injured in several days of protest.
German Foreign Minister Minister Guido Westerwelle on Friday reiterated his call to Cairo to abstain from a violent crackdown.
He said the German government had told Egypt "that stabilizing the country could only be possible if democracy and freedom" were granted.
A widespread shutdown of internet and cell phone networks - which have been widely used to organize protests - was reported early on Friday after reports of more sporadic shutdowns throughout Thursday.
The country's Interior Ministry warned of "decisive measures" late on Thursday with opponents of the regime expected to rally for a fourth day. Along with text messages, appeals were posted on social networking site Facebook for fresh demonstrations "to demand the right to live with freedom and dignity."
Call to different faiths
Pages on social networking websites had listed mosques and churches where protesters were expected to gather.
"Egypt's Muslims and Christians will go out to fight against corruption, unemployment and oppression and absence of freedom," said the Facebook page, claiming that some 70,000 people had signed up to support the demonstrations. Similar comments were published on the micro-blogging website Twitter.
Amnesty International's Deputy Director for the Middle East and North Africa, Hassiba Hadj Sahraoui, told Deutsche Welle there were fears that violence would escalate further.
"We are expecting a lot of people to demonstrate and on the other hand we have the security forces who have shown the determination to quell demonstrations and who are using excessive force. The demonstrators seem undeterred."
Crackdown on Muslim Brotherhood
At least eight senior officials of the Muslim Brotherhood opposition group were arrested in an overnight crackdown. Egypt's government accuses the group of attempting to exploit protests against poor living standards and authoritarian rule, for its own "hidden agendas."
Nobel Laureate and key dissident figure Mohamed ElBaradei, who arrived in Cairo late on Thursday following a visit to Vienna, said he would take part in the protests.
ElBaradei, a former head of the International Atomic Energy Agency, said Mubarak's government had left Egyptians little choice but to take to the streets.
Nationwide demonstrations against Mubarak, who has led the country for three decades, began on Tuesday. These have been largely led by people under the age of 30, who make up two-thirds of Egypt's population, and follow similar protests in Algeria and Tunisia.
Facebook and Twitter have played a major role, carrying tips on avoiding arrest and coping with tear gas, as well as being used to organize rallying points.
Author: Richard Connor (Reuters, AFP, AP, dpa)
Editor: Andreas Illmer