Tens of thousands have marched on Washington and cities around the world in support of gun control.

Organizers of the March for Our Lives rally hoped the protest would match last year's women's march, which exceeded predictions of 300,000 demonstrators.

Summoned by student survivors of the Florida school shooting, protesters held signs reading "We Are the Change" and "Keep NRA Money Out of Politics".

Pictures showed a packed Pennsylvania Avenue from the stage near the Capitol, back towards the White House.

Large rallies also unfolded in several US cities including Boston, New York, Chicago, Houston and at the site of the February 14 mass shooting at Marjory Stoneman Douglas High School in Parkland, Florida, that left 17 people dead.

Protesters also flocked outside the US embassy in London to demand an end to mass shootings, pledging to "stay angry" until gun laws are reformed.

Relatives of Dunblane massacre victims were among hundreds of people who protested outside the US Consulate in Edinburgh in solidarity with other protests around the world, of which there were more than 800.

Organisers hope the passions of the crowds around the world and the youth of speakers will translate into a tipping point that will lead to tighter gun regulation.

16-year-old Talia Rumsky, who was in class at Marjory Stoneman school in Parkland, Florida, when gunman Nikolas Cruz opened fire, told how she is marching for change.

She said: "I'm really here to make sure we can make our voices heard, so people are empowered to make sure we vote in legislators so this doesn't happen again.

"So we can avenge those who were stolen from us because someone thought it was OK to own weapons of mass destruction."

A new poll conducted by The Associated Press-NORC Centre for Public Affairs Research found that 69% of Americans think gun laws in the United States should be tightened.

The poll also found that nearly half of Americans do not expect elected officials to take action.