The Egyptian government's crackdown on protestors intensified Friday with access to most forms of mass communication, including the Internet, mobile and SMS down, even as United Nations Secretary General Ban Ki-moon warned that "freedom of expression should be fully respected."

As the country braced for huge antigovernment protests on the traditional day of prayer, the government appeared to have unplugged most means of communication—including social network Facebook and Twitter—that activists had been using to coordinate action across the country. Landline calls placed from outside the country, however, were connecting.

Government-owned Telecom Egypt runs the country's fixed-line network. Attempts to connect to the websites of several Egyptian ISPs, including EgyptWeb, TeData and Purenet all failed.

U.K.-headquartered Vodafone Group PLC said in a statement that all mobile operators in Egypt had been "instructed to suspend services in parts of Egypt. Under Egyptian legislation, the authorities have the right to issue such an order and we are obliged to comply with it." It said the Egyptian authorities will be clarifying the situation in due course.