Facebook and Twitter have been blocked in Egypt as hundreds of Egyptian activists stormed through Cairo’s streets demanding the resignation of the country’s president.

Twitter confirmed that its service had been blocked in Egypt, indicating a probable government crackdown on technology that could disseminate information about the widening anti-government demonstrations.

“We can confirm that Twitter was blocked in Egypt around 8am (Pacific Time, 1600 GMT) on Wednesday,” Twitter confirmed on the @twitterglobalpr feed.

“It’s impacting both Twitter.com & applications. We believe that the open exchange of info & views benefits societies and helps govts better connect w/ their people.”

Egypt protests: Twitter down Facebook still running

According to Herdict.com, which tracks government attempts to block internet sites, Egyptian authorities appear to have also taken action against other popular communications sites, such as Facebook, YouTube, Person.com and veoh.com.

The internet crackdown was designed to make it difficult for campaigners to organise flash mobs.

However, it appears that such actions have been partially circumvented, because many users in Egypt still reported being able to access the sites, including by mobile telephones.

The Egypt social networking block comes as hundreds of activists in Egypt defied a ban to gather for a second day of protests on Wednesday demanding the resignation of president Hosni Mubarak.

“The government is intent on guaranteeing the freedom of expression by legitimate means,” Prime minister Ahmed Nazif said.

Police fired tear gas to disperse a crowd in the commercial region of Cairo while, in the southern city of Assiut, about 100 activists were arrested by baton-wielding officers.

The previous day, four people were killed in the protests, including one policemen, and 250 people were injured

Organisers called for Egyptians ‘to be brave and join us’.

“Change must happen. It must,” said a Cairo butcher.

Protesters faced massive police presence, with officers in riot gear posted on bridges across the Nile and outside politically sensitive buildings.

Campaigners, inspired by a recent revolution in Tunisia, are calling for an end to Mubarak’s 30-year rule, which has seen rampant poverty, rising prices and high unemployment.