Egypt's last working Internet service provider, the Noor Group, has went down, a US Web monitoring company said, leaving the crisis-torn country completely offline.

Renesys, a New Hampshire-based firm that monitors Internet routing data in real time, said the Noor network "started disappearing from the Internet" around 2046 GMT.

"They are completely unavailable at present," Renesys vice president and general manager Earl Zmijewski said in a blog post.

Attempts by AFP to access noor.net and other websites in Egypt serviced by the company, such as the Egyptian stock exchange site at egyptse.com, were unsuccessful.

Egypt's four main Internet service providers -- Link Egypt, Vodafone/Raya, Telecom Egypt and Etisalat Misr -- cut off international access to their customers on Thursday.

The move left the Noor Group as the only working Internet provider in the country rocked by days of protests against President Hosni Mubarak.

Mobile telephone networks have also been severely disrupted in Egypt along with the Internet.

Activists have used mobile phones and the Internet to organise the most serious anti-government demonstrations in decades, protests inspired by the uprising in Tunisia.