Thousands of Sri Lankan Tamils demonstrated outside the United Nations headquarters in Geneva on Wednesday calling for an end to "genocide".
They demanded that the UN should intervene to save the population of the northern areas of their homeland, where government forces have recently launched a widescale offensive against the Tamil Tiger rebels.
The rally, called by the Association of Young Tamils in Switzerland, was attended by more than 10,000 people, the Swiss News Agency reported. They had come from all over Switzerland and also from France.
The association says 470,000 civilians are affected by the fighting, and warned that thousands of them could be killed in the near future as villages are shelled by government forces.
The UN and the Geneva-based International Committee of the Red Cross (ICRC) says several hundred civilians have been killed since the beginning of the year. The ICRC reported on Wednesday that more than 300 patients and staff had been forced to flee a hospital in the Tamil area after it came under shelling.
The conflict has been going on for 37 years. The Tigers want a separate state in the north and east of the island. They say they are discriminated against by the Sinhalese majority.
Sri Lankan President Mahinda Rajapakse says his troops will continue fighting until they have won a "total" victory over the Tigers.
Throughout the period, both sides have been accused of serious human rights violations.