By Frances Harrison BBC correspondent in Colombo

Clashes between Muslims and Tamils have spread across eastern Sri Lanka, reportedly leaving one person dead and at least 50 injured in a number of separate attacks.

The clashes which first began in Muthur town in Trincomalee district have now spread to the Valaichchenai area in Batticaloa district.

It is still unclear exactly why they are taking place now.

A curfew has now been imposed in the Valaichchenai area but reports from Batticaloa say it failed to prevent a grenade attack late in the day which killed one civilian and injured about 20 people.

This followed a number of small incidents in Valaichchenai earlier in the day where three buses were damaged in front of the police station and an ambulance attacked on its way back to the area from Batticaloa.

Grenade attack

Journalists reported a grenade attack in the Valaichchenai market in the morning in which four people were injured and taken to the local hospital.

As night fell, shops in Valaichchenai were reportedly still burning.

Muslims feel excluded from the current peace process between the government and Tamil Tiger rebels

There are also reports that several shops belonging to Muslims were set on fire in another area and more minor injuries in separate clashes between the two communities.

Meanwhile, there were initial signs of trouble brewing in Ampara district in the morning but it appears the local authorities have calmed the situation there.

And in Muthur Town where the tension first started several days ago a high-level meeting of political and religious leaders was being held to try to resolve the problem.

Serious consequences

Several theories have been put forward for why this is happening now.

Some argue that Muslims as Sri Lanka's third largest community feel excluded from the current peace process between the government and Tamil Tiger rebels.

The prime minister's efforts are threatened

Others say they are fed up with extortion and harassment allegedly at the hands of the rebels.

Some of the media have suggested extremist Islamist groups with international links are involved, but Muslim politicians deny such groups even exist in Sri Lanka.

But there are also fears being expressed about whether those who oppose the peace process in Sri Lanka might be helping to incite the trouble - though there is no proof that the frustrations being expressed are not local ones.

Officials say they hope they can prevent the tension from spreading but if it does there are likely to be serious consequences for the peace process.