Egyptians say the Twitter Web site is blocked on all Internet Service Providers in their country, a representative of Harvard University's Herdict Web monitoring service told Reuters on Tuesday.

But Twitter users within Egypt are currently sending Tweets, short 140-character messages, via SMS text messages and through third-party applications, the center said as thousands of Egyptians took to the streets to protest President Hosni Mubarak's 30-year rule.

Jillian York, a project coordinator at Harvard's Berkman Center for Internet & Society, which runs the Herdict Web accessibility monitoring service, said in an email that she had confirmed with users in Egypt that Twitter.com is in fact blocked on all ISPs.

(Reporting by Alexei Oreskovic, editing by Peter Henderson and Gerald E. McCormick)

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