Iranian expatriates marched in Brussels on the eve of the first anniversary of Mahsa Amini, a 22-year-old woman whose death in custody ignited Iran’s biggest anti-regime protests.

Thousands of demonstrators, holding up pictures of Amini and many others killed in the protests, called for the overthrow of Iran's theocracy and the establishment of a democratic republic.

Organizers said they had also demanded a unified European Union policy to hold Iran's Shiite clerical rulers accountable for abuses.

Iranian communities in several European cities have kept several rounds of rallies in support of protests in Iran and to demand the closure of Islamic Republic’s missions in Europe.

The protests that followed the death of Amini, arrested for allegedly flouting the Islamic Republic's mandatory dress code, spiraled into the biggest show of opposition to the Iranian authorities in years.

Over 500 people including 71 minors were killed, hundreds injured and thousands arrested, rights groups say, in unrest that was eventually crushed by security forces.

The Tehran government has accused the United States and Israel and their local agents of fomenting the unrest to destabilize Iran.

Iranians are bracing for rallies on Saturday while regime forces have been deployed at strategic regions. Heavily armed military forces have been stationed in restive areas, particularly in Kurdish majority cities, and anti-riot police forces are mushrooming on streets of major cities.