One of two protesters staging a hunger strike will suspend his fast today as thousands of people take to the streets to march in protest against the Sri Lankan government's offensive against Tamil Tiger rebels and alleged human rights abuses.
The march - led by student groups - will start at Embankment in central London and will end in Green Park.
A group of around 500 Tamil supporters has been occupying London's Parliament Square for five days.
Two of the protesters - Sivatharsan Sivakumaraval, 21, and Prarameswaran Subramaniam, 28 - have been on a hunger strike since Monday but today Mr Sivakumaraval agreed to suspend his fast for 10 days.
Supporters had feared the pair were close to suffering renal failure.
Last night both men agreed to take liquids after politicians pledged to help them take part in talks on the plight of the Tamils living in Sri Lanka.
Simon Hughes, Liberal Democrat MP for North Southwark and Bermondsey, is trying to arrange for a delegation of protesters to travel to the UN, Washington and Brussels with MPs for political talks.
Tamil supporters want to see a ceasefire and the delivery of humanitarian aid to civilians in the designated "safe zone" in the north of the country.
Mr Hughes said Mr Sivakumaraval had agreed to accept some food later today providing he was allowed to accompany Des Browne, the government's special envoy to Sri Lanka, to the talks.
According to Mr Hughes, Mr Sivakumaraval was also hoping to speak at a rally following today's march.
He also said the protesters had received police permission to continue their occupation for another 48 hours and would apply for it be extended into next week.
He said: "There's very wide political support for urgent action in Sri Lanka to avert a terrible crisis in lives and liberty.
"Politicians from across the parties in the UK are willing to work with the community here to try to get political movement in the next few days."
He continued: "There's also a strong view that an interfaith approach, including the Buddhist community, might go to Buddhist leaders and the government in Sri Lanka, which would be a very worthwhile initiative.
"The evidence from Sri Lanka is that we're on the edge of more serious loss of life and real urgency is needed if we are to have a chance of avoiding more bloodshed and the loss of hundreds more lives."
The protesters want the UK Government to take action to help protect the Tamils in their homeland.
The Sri Lankan government has rejected international calls for a ceasefire, claiming it is on the verge of defeating the Tamil Tigers, a rebel group fighting for an independent homeland.
The United Nations said up to 150,000 people are trapped in the war zone in the north of Sri Lanka.
Foreign Secretary David Miliband has insisted the Government was "very concerned" about civilians caught up in fighting in Sri Lanka.
The two hunger strikers earlier signed statements proclaiming they were on "hunger strike till last breath with full heart" and would not stop until their demands were met.
The demands include a ceasefire and that food and medical aid be allowed to reach civilians.
Lakshmi, a medical student at King's College London, said: "We are desperate. People have the wrong impression of the Tamil Tigers. They've been called terrorists."
The 21-year-old, who did not want to give her surname for fear she would not be allowed to travel through Sri Lanka, continued: "We are trying to tell people that they are freedom fighters.
"What we call the Tamil Tigers are actually carpenters, fishermen and normal people in society.
"There's very wide political support for urgent action in Sri Lanka to avert a terrible crisis in lives and liberty."