A doctor has criticised Ed Miliband for his role in Parliament rejecting the principle of Britain taking part in a military strike against Syria.
The doctor, from the charity Hand in Hand for Syria, is known as Dr Rola.
She treated victims of a suspected napalm attack on a school in northern Syria earlier this week.
Dr Rola told the BBC's Newsnight she would invite Mr Miliband and his family to spend time in Syria to experience the horrors suffered by its people.
The UK opposition leader's office said it had not seen the Newsnight interview but said the Labour leader had made clear that finding a diplomatic solution to the Syrian crisis should be at the top of the agenda at next week's G20 summit.
In an opinion piece in the Guardian, Mr Miliband said he did not agree that Thursday's vote in the House of Commons meant that Britain cannot make a difference to the "innocent civilians of Syria who are suffering such a humanitarian catastrophe".
Dr Rola said: "I'd like him to spend a day in one of the civilian areas under constant shelling, watching the warplanes above us throw all sorts of weapons on to civilians, and fear for the safety of his family.
"Spend just one day and one night in a tent in one of the camps where the homeless now live and drink sewage water, and try his luck with typhoid fever and no medication."
Labour shadow cabinet member Diane Abbott responded to Dr Rola on Newsnight.
She said: "To say that MPs refused to give Cameron a mandate for bombing this weekend means that we don't care, that we don't think the scenes are horrific, is to misunderstand.
"We debated this for eight long hours and there was a consensus, even among people who voted for Cameron, that bombing the Syrians this weekend would not help matters."
Senior politicians at Westminster have been trying to limit the diplomatic fallout from Parliament's decision not to sanction British involvement in any military intervention.
UK Prime Minister David Cameron has spoken by telephone to US President Barack Obama to stress Britain's support for a "firm response" on Syria.
Mr Miliband has insisted that he remains committed to the "special relationship" between the UK and the US.
Mr Obama said he fully respected Mr Cameron's approach, when they spoke during a 15-minute phone call on Friday. The tone of the conversation was said to be friendly.
The White House believes President Bashar al-Assad's regime was responsible for the chemical attack on 21 August which the US says killed 1,429 people in the Ghouta suburb of Damascus.
UK ministers ruled out British involvement in any military action after MPs blocked a government motion calling for military action if it was backed up by evidence from UN weapons inspectors.
The US said it would continue to seek a coalition for military intervention and France said its resolve about the need to act was not changed by the UK vote.
More than 100,000 people are estimated to have died and at least 1.7 million refugees displaced since the conflict in Syria erupted in March 2011.
The violence began when anti-government protests during the Arab Spring uprisings were met with a brutal response by the Syrian security forces.
President Assad's regime has blamed foreign involvement and armed gangs for the conflict.