The Liberation Tigers of Tamil Eelam have urged the United Nations to recognise 'Tamil sovereignty' to end the 25-year-old ethnic conflict in Sri Lanka [Images], accusing the Sri Lankan government of committing excesses against the minority community in the country.

'We urge you to consider recognising Tamil sovereignty as a constructive approach to end the five decades long, large-scale, and serious rights violations against the Tamil people,' the LTTE political head B Nadesan said in a letter to the UN Secretary General Ban Ki-Moon on Wednesday.

'It should also be obvious to the international community that there is only one path open to regain the rights of the Tamil people and that is for the international community to recognize the sovereignty of the Tamil nation,' Nadesan said.

The political head of the LTTE alleged in the letter that the Sri Lankan army was involved in the attack on Monday at Madhu that led to the death of 18 civilians, including 12 school children.

'On 28 January, at 2.30 pm, a Sri Lankan military Deep Penetration Unit attacked a civilian bus on the Madhu-Palampiddy road in the Mannar district killing 18 civilians including 12 children,' Nadesan said in the complaint lodged with the UN Secretary General.

'The attackers would have known that buses at that time carry school children returning home from school. This attack on a bus with scores of children, therefore, deliberately targeted the children. Among the 18 civilians killed were 12 children aged from 8 to 16,' he said.

Refuting the LTTE charges, a Sri Lankan military spokesman said the attack took place in the rebel-controlled area and the involvement of Sri Lankan army does not arise.

Nadesan, the political chief of the Tamil Tigers, in his letter to the UN Secretary General accused the Sri Lankan military of being responsible for aerial bombing of a village in Mullaithivu in which seven children were killed on January 4.

'Since the present President of Sri Lanka (Mahinda Rajapaksa) assumed office in November 2005, as many as 2,056 Tamil civilians including 132 Tamil children have been massacred by the Sri Lankan State Forces,' he wrote.

He alleged that the 'pace of civilian killing by the Sri Lankan State, after unilaterally abrogating the ceasefire agreement of February 2002, after evicting the ceasefire monitoring mission, the SLMM, and after adamantly refusing to allow UN human rights monitoring body continues to increase.'

Nadesan said it should be 'obvious to the international community by now that our organisation has demonstrated its readiness to cooperate with the international community.'

Nadesan said the LTTE has consistently called for the 100 per cent implementation of the internationally-supported ceasefire agreement of February 2002 for regaining the rights of the Tamils.

'We also cooperated fully with the Norwegian facilitators, respecting the wishes of the international community, in drafting and implementing agreements on humanitarian relief, de-escalation and post-tsunami reconstruction that were later abrogated by the Sri Lankan State,' Nadesan said.

Thousands of people have been killed since the LTTE launched its separatist campaign to form an independent State for the Tamils in the island nation.