Mobile operator Vodafone accused the Egyptian authorities on Thursday of using its network to send pro-government text messages to subscribers, as telecom firms became further embroiled in the crisis.
Another mobile boss, the chief executive of Orascom Telecom, protested against President Hosni Mubarak's rule in the main Cairo square on Thursday and said any damage to his company arising the unrest was a price worth paying.
Vodafone, the world's biggest mobile operator by revenue, was told by the government last week to switch off its network in Egypt after the anti-Mubarak protests broke out.
Other operators were also forced to cut their service and rights groups have heavily criticised the development.
Vodafone said at the time that it had no choice and on Thursday it stepped up its attack, saying it was being forced to send text messages without making clear the attribution.
The current situation regarding these messages is unacceptable, it said.
British Foreign Secretary William Hague called for a halt to interference with the Internet and mobile phones, and for an end to the harassment of journalists..
The abuse of Internet and mobile networks and, in particular, today's increased intimidation and harassment of journalists are unacceptable and disturbing, he said in a statement.
Vodafone said the Egyptian authorities had told the mobile networks of Mobinil, Etisalat and Vodafone to send messages to the people of Egypt and had been doing so since the protests broke out against President Hosni Mubarak's 30-year rule.
One text message sent on February 2 and seen by Reuters announced the location and timing for a mass demonstration to support Mubarak.
Vodafone Chief Executive Vittorio Colao told reporters on Thursday that voice calls had been switched off for 24 hours last Friday, that data services which allow access to the Internet had been down for five days, and that text messages were still down for subscribers.
A source familiar with the situation told Reuters the authorities had ordered Vodafone to switch the network back on, for just long enough to send the messages.
Etisalat was not available to comment and emails and phone calls to Mobinil executives were not returned. Mobinil is jointly owned by Orascom and France Telecom.
These messages are not scripted by any of the mobile network operators, Vodafone said.
Khaled Bichara, the chief executive of another major telecom firm Orascom, was seen by a Reuters reporter in the main Tahrir, or Liberation, Square, protesting against Mubarak's rule.
Asked on BBC TV if his firm was suffering from the protests, Bichara said: Of course, but sometimes that's the price to pay. He later told Reuters by telephone that if the authorities objected to his conduct they could call on his boss to sack him.
I am there on a personal capacity, he said. I am the CEO of Orascom Telecom. I have no licenses in the company I work for. The licenses are for the company, not the person, so if they are not happy they can call my boss and he can fire me and that's about it.
Naguib Sawiris, a well known businessman whose holding company owns more than half of Cairo-based Orascom, called on Thursday for the formation of a national unity government composed of technocrats and independent politicians.
In an interview with the BBC, he said Mubarak should be offered a dignified way out.
Our president is a military man who fought for this country, he said. Many of us, including myself, do not agree to have him humiliated.
(Additional reporting by Alison Williams and Alexander Dziadosz in Cairo, Alastair Sharp in Toronto and Adrian Croft in London; Editing by Andrew Dobbie)