The Sri Lankan military is killing hundreds of Tamil civilians each day. Last Sunday alone, a thousand people were killed by cluster bombs, artillery and machine gun fire. On Monday, hundreds died when Sri Lankan forces used them as human mine-sweepers and human shields to advance against the Tamil Tigers.

This "slaughter" of civilians, as Human Rights Watch has condemned it, has intensified since January. Over 5,000 Tamils have been massacred in the past three months alone.

Crucially, this genocide by the Sri Lankan state has been enabled by the international community, including Britain. This is why tens of thousands of British Tamils have been protesting outside Parliament here for several weeks.

We are British citizens, but our government is ignoring us and turning a blind eye to the ongoing massacres of our relatives and community in Sri Lanka.

Sri Lanka as a country was evicted from the UN human rights council last year for its gross violations of the human rights of its people. Sri Lanka does not let independent journalists report freely. The current government has been accused of being complicit in many abductions and killings of journalists and others.

The UK and other western states have suggested that by destroying the Tamil Tigers, Sri Lanka can be made peaceful. This is a profound misunderstanding of the state-racism and ethnic supremacy at the heart of the Sri Lankan crisis – a crisis that has now become genocide.

Britain is deeply implicated in this crisis.

When in 1948 Britain, the colonial power, granted independence to Sri Lanka, the Westminster-style democracy London set up allowed a pernicious Sinhala chauvinism to capture the state and begin the 60 years of violence and oppression the Tamils have now endured.

In 1977, after three decades of discrimination and state-backed mob violence, the entire Tamil political leadership united behind a demand for an independent state comprising the Tamil homeland as the only way to escape oppression.

The Sinhala-dominated state responded with violence, and a few years later, in 1983, a Tamil armed struggle emerged in response. This resistance to the Sinhala state is led by the Tamil Tigers or LTTE – Liberation Tigers of Tamil Eelam. Until 1983 Tamils have tried through many of their democratically elected leaders and parties to resolve this injustice by negotiations and peaceful means. Even during the armed struggle, LTTE has many times attempted to negotiate with successive Sri Lankan governments. As recently as 2002, a ceasefire agreement was negotiated between the government and the LTTE by the international community. Just as before, the Sri Lankan state abrogated from this agreement unilaterally in January 2008.

Since 1983, the problem in Sri Lanka has been characterised by western states as conflict, rather than state chauvinism. They have sought to support the Sinhala-dominated state and pressure the LTTE to "make peace".

The Tamils in Sinhala-dominated Sri Lanka face the same crisis as the people of Kosovo under Serbian rule. The international community could not make the Serbian state led by Milosovic cease its attempts to wipe out the people of Kosovo, and ultimately Kosovo was granted independence to assure their safety.

Having abandoned the Tamils to majoritarian tyranny, Britain has consistently ignored the Sinhala chauvinism deeply embedded in the Sri Lankan state. The UK has cynically sold weapons to the Sinhala military and tried to pass off the agitation by Tamils as one of poverty, merely requiring "development".

We want Britain to compel the racist regime in Sri Lanka to cease its genocide. As a member of the UN Security Council, a close ally of the US and a member of the EU, Britain has the ability to do this. As the former colonial power that placed the Tamils at risk, and as a state that has sought explicitly to champion democracy and freedom, it has a moral obligation, too.

Remember, most British Tamils have direct relatives – mums, dads, brothers, sisters, nephews and nieces – left back in the war zone. They are genuinely concerned for their safety and whereabouts.

That is why Britain's Tamils are protesting outside Parliament day and night.