COLOMBO, July 24, 2008 (AFP) - Sri Lanka will on Friday mark a quarter of a century since the country's worst ethnic riots claimed scores of lives, but 25 years on there is little prospect of peace on the island.

In July 1983, the country -- where ongoing fighting in a civil war between Tamil rebels and the government continues to simmer -- experienced a nationwide wave of deadly attacks, now known as 'Black July.'

Mobs attacked a Tamil train passenger and burnt him alive at Colombo's busiest railway station, while hundreds of others outside the capital were lynched or hacked to death.

Officials say the number of Tamils massacred was between 400 and 600, but some Tamil groups say as many as 6,000 were killed.

The week of violence began after separatist Tamil Tiger guerrillas carried out their most successful attack to date by killing 13 government soldiers in the northern peninsula of Jaffna.

The government initially tried to hold a mass burial for the 13 soldiers at a cemetery in Colombo, but relatives and others demanded individual funerals, sparking clashes with police.

The incidents resulted in widespread violence across the island and marked a watershed in Sri Lanka's conflict, which dates back to 1972 when a group of Tamil youngsters took up guns and formed the Tiger movement.

One Tamil man who did not want to be named but who survived a July 1983 attack said he had 23 wounds on his body and was left on the roadside only because his attackers thought he was dead.

'It was a Sinhalese mob that tried to kill me, but it is also my Sinhalese friends who took me to hospital and made sure I received treatment,' he said, adding Tamil people in Colombo were still living in fear.

At the country's main prison, 53 Tamil detainees were hacked to death during the week, the origin of the militants' practice of wearing cyanide around their necks in case they are captured by security forces.

Ethnic tensions had simmered since independence from Britain in 1948, but the 1983 riots saw an upsurge in Tamil militancy and raised the conflict beyond a law and order problem into a full blown insurgency.

The Black July events strengthened the resolve of the Liberation Tigers of Tamil Eelam (LTTE), according to Constitutional Affairs Minister Dew Gunasekara, writing in the state-run Daily News.

'The ugliest and the most barbarous event in post-independent Sri Lanka entered the pages of history 25 years ago,' he said.

'Some people ask why these blackest events are being reminded ritually in the month of July year after year. I believe that it is of no other reason than to reassure ourselves that such an event should never be allowed to recur.'

Five years ago, Sri Lanka's then president Chandrika Kumaratunga extended a formal apology to minority Tamils for the events of 1983, but many say the wounds remain raw.

Tamil politician and former Tiger guerrilla Dharmalingam Sithadthan says Sri Lanka's current conflict might not have deepened to the current extent if the government of 1983 had not allowed the July riots to drag on.

'They allowed it to drag on for a week,' Sithadthan said. 'Since 1983, much more terrible things have happened to all communities.'

There are no accurate figures for the number of people killed since the conflict began, but widely used estimates place the death toll since 1972 at around 70,000 people and many more injured.

Tamil lawmakers say their minority community is being persecuted and singled out for harsh treatment, and international rights groups have criticised the authorities for abuses.

Last year, Sri Lanka's Supreme Court ruled the forced eviction of hundreds of Tamils from Colombo was illegal.

With Sri Lanka formally pulling out of a moribund truce in January this year, the fighting has deepened and the authorities have ruled out fresh peace talks unless the rebels laid down arms first, a call already rejected.

'As a country, we are worse off today than we were 25 years ago,' said Sithadthan. 'Since 1983, we have suffered much deeper wounds. There is no sign of a quick end to the bloodshed.'