Hundreds of demonstrators have gathered in London in a show of solidarity with protesters across the Middle East and North Africa.

The demonstration took place in Trafalgar Square, with live link-ups to the Syrian towns of Deraa and Idlib as part of Amnesty International's global day of action.

Similar events were held in 21 countries across the globe, according to the human rights group.

Western diplomats have warned that Syrian officials involved in the brutal suppression of anti-regime protests will be held accountable for their actions.

Salil Shetty, Amnesty International secretary general, told the demonstration in London: "Our message to the people of the Middle East and North Africa is that you are not alone in your struggle. We are with you.

"Our message to the governments of the Middle East and North Africa is that you will be held to account. The world is watching."