United Nations Environment Programme chief Erik Solheim today expressed concern over the death of 13 people in police firing during violent protests against the Vedanta group's copper smelter plant in Tamil Nadu's Tuticorin district.

The UNEP executive director general said he was 'worried' and hoped that protests would remain non-violent.

"We are concerned over this and paying our condolence to those who have lost their lives," he said.

"Let me say my prayers and extend my condolences to the families of those who died. This shall not happen," Solheim said, during a media interaction in Kochi.

Protests should be without violence and the police should not use force, he said.

"We are very worried and hope that solutions can be found," the UN official said, when asked about his views on the killing of people protesting against the copper plant on May 22.

Solheim, who was in Kochi to visit the Cochin international airport, the world's first fully solar-powered airport, called for a 'dialogue with the people' before implementing infrastructure projects.

He also emphasised the need for environmental protection when going ahead with such projects. Violence erupted in Tuticorin on May 22 and 23 as locals took to streets, demanding closure of the copper factory over pollution concerns.

In a filing with the Bombay Stock Exchange, Vedanta said the Tamil Nadu pollution control board had on May 23 ordered disconnection of electricity supply and closure of the copper plant.  -- PTI