Why are we asking this now?

In recent days large crowds of Tamil protesters have taken to the streets of London to highlight the plight of thousands of Tamil civilians caught up in the apparent endgame of a long and vicious civil war in Sri Lanka. The demonstrators are demanding that Britain use its influence to try and enforce a ceasefire between the Sri Lankan army and the fighters of the Liberation Tigers of Tamil Eelam (LTTE). Police arrested four people – one for violent disorder – after scuffles broke out when officers moved protesters off a bridge into Parliament Square.

Why are protesters now taking to the streets?

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The fighting between the LTTE and the government forces may now be in its last phase. Apart from a tiny patch of jungle no more than one mile by two, over which the two sides were last night still fighting, the remnants of a once powerful LTTE force are now holed up in an area measuring no more than 7.7 square miles. This area is a so-called "no-fire zone". The problem is that also squeezed within this no-fire zone are anywhere between 100,000 and 190,000 Tamil civilians. The Sri Lankan government has rejected numerous international calls for a ceasefire to allow the evacuation of civilians – yesterday another UN special envoy added his name to the growing list – but at the same time it has so far stood back from ordering a major assault on the no-fire zone that would almost certainly result in massive civilian casualties.

"I am deeply concerned for the lives of over 100,000 civilians trapped in the 14 square km area of the Vanni declared by the Government of Sri Lanka. Large numbers of civilians have been killed or wounded. Following reports that LTTE fighters now have been pushed entirely into this zone, many more are at risk of losing their lives," said Walter Kaelin, the Representative of the UN Secretary-General on the Human Rights of Internally Displaced Persons. "I urgently repeat my call to the LTTE to allow all civilians under its control to leave this zone and to seek safety elsewhere. I also call on the Government of Sri Lanka to scrupulously respect the no-fire zone."

What are conditions like in the no fire zone?

Journalists have been banned from getting anywhere near the war zone, apart going on sanitised officially organised visits escorted by the military, so the picture is not entirely clear. Aid groups say conditions there are dire; there is insufficient food, water and medicine and people are pushed together under makeshift plastic shelters. "It's desperate, desperate, desperate," said Sarah Crowe, a senior regional official with Unicef. People have been stuck there for months and while thousands of civilians have managed to slip out of the no-fire zone, many more are trapped. UN officials say that the LTTE is preventing people from leaving in order to provide themselves with a bulwark against an onslaught by government troops. "The government has said this is a hostage situation," said Gordon Weiss, a Colombo-based spokesman for the UN. "They have indicated they are going to play a wait and see game and to seal this area."

What has been the civilian toll?

There are no official figures but in recent weeks there have been reports that hundreds of civilians are being killed every week and many more wounded, having been caught up in crossfire and shelling by both sides. Medical facilities in the zone are all but non-existent. Those who are able to get to the evacuation points on the coast are taken by ferry south to Trincomalee where, under heavy guard, they are moved for treatment in hospitals. After that they are taken to internment camps. The Sri Lankan authorities say they are doing this to ensure that no LTTE fighters are hiding themselves among the civilian wounded. Mr Weiss said around 65,000 civilians may now be held inside these camps.

How long has this conflict been going on?

The fighting between the Tigers and the government has taken place since as early as 1983. The Tigers, led by Velupillai Prabhakaran, have been fighting for a separate homeland for the largely Hindu Tamils, claiming that the Sinhalese Buddhist majority has long discriminated against them. The Tigers have used brutal tactics, including the suicide bombing of civilian targets, in addition to the many Sri Lankan politicians they have killed. At least 70,000 people have died in fighting but the death toll might even be much higher – possibly double that.

Why have events happened so quickly?

President Mahinda Rajapaksa won power in 2005. Following the breakdown of a ceasefire agreement between the Tigers and the government in January 2008, Mr Rajapaksa vowed to undertake a "war for peace" and to destroy the rebels within a year. The military has not achieved that but has been able to squeeze the rebels into enclaves. In November, government troops took the town of Kilinochi, the rebels' de facto capital. Since then they have taken every remaining stronghold. The army now says that every LTTE village and town is in the control of government forces.

Why has there been such controversy surrounding the government's tactics?

The government assault upon the rebels has been accompanied by a crackdown on critics. Various groups have criticised the government for an assault upon the media. Amnesty International said that since 2006 at least 14 media workers have been killed and hundreds of others harassed and attacked by both sides of the conflict. More than 20 have fled the country in response to death threats. Among the most high profile killings was that of Lasantha Wickrematunga, editor of The Sunday Leader and an outspoken critic of the government. The authorities have denied accusations – made most famously by Mr Wickrematunga himself in an article published posthumously – that they were involved in his killing.

What has the international community done to end the violence?

There have been widespread calls for a ceasefire to allow an evacuation of civilians but there has been remarkably little action. India, the most influential regional power, has asked Sri Lanka to find a political settlement for the Tamils – of which there is a large population in Southern India. But by pitching the operation of the government troops in the language of so-called "war on terror", Mr Rajapaksa may have insulated himself from anything other than words. Yesterday Foreign Secretary David Miliband, became the latest to express concern, saying: "Recent reports suggesting that the Sri Lankan military have now captured all the territory outside the so-called no-fire zone and that fighting is now going on inside the zone, where the civilian population is concentrated, are deeply worrying." These words are unlikely to assuage the anger of London's protesters, however.

Can there be a military solution to Sri Lanka's conflict?

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Yes...

* Destroying the Tigers now would leave them without a stronghold and potentially without a leader

* The government is better at preventing money getting to them

* The government's actions against the Tigers have been popular among the Sinhalese majority. They will use that to seek re-election

No...

* The last remnants of the Tigers will hole up in patches of jungle and fight a hit-and-run war as they once did

* The political demands of the Tamil population have to be addressed. There is too much evidence they are treated like second-class citizens

* The Tigers still receive significant support from outside Sri Lanka