Thousands of Algerians defied a government ban on protests and a massive deployment of riot police to rally in the capital Saturday, demanding democratic reforms a day after similar protests toppled Egypt's authoritarian leader.

Heavily armed police tried to seal off the city of Algiers, blocking streets, lining up along the march route and setting up barricades outside the city to try to stop busloads of demonstrators from reaching the capital.

But despite the heavy security, thousands flooded into downtown Algiers, clashing with police who reportedly outnumbered them at least three-to-one. A human rights activist said more than 400 people were arrested.

Tensions have been high in this sprawling North African nation of 35 million since five days of riots in early January over high food prices. Despite its vast gas reserves, Algeria has long been beset by widespread poverty and high unemployment, and some have predicted it could be next Arab country hit by the popular protests that have already ousted two longtime Arab leaders in a month.

Protesters chanted "No to the police state!" and "Bouteflika out!" — a reference to President Abdelaziz Bouteflika, who has led the nation since 1999.