(Corrects ethnicity of aid workers to Tamil from Muslim in second paragraph after police erroneously identified the men as Muslim) (Updates with presidential spokesman comment, details)
COLOMBO, June 4 (Reuters) - The Sri Lanka Red Cross on Monday demanded a probe into the killing of two of its volunteers amid a rash of abductions and murders in a renewed civil war, and urged the government and Tamil Tiger rebels to respect human rights.
The corpses of the two Tamil men were found on Sunday dumped in the gem-mining district of Ratnapura, southeast of Colombo, two days after they were taken away by men who identified themselves as police at a train station in the capital.
Police have denied any involvement in the killings, discovered after President Mahinda Rajapaksa said most complaints about abductions -- many of which are levelled at state security forces -- were false.
"The movement calls upon the Sri Lankan authorities to carry out an immediate and comprehensive investigation into the killings," Sri Lanka Red Cross Director General Nevil Nanayakkara said in a statement.
"The movement reminds the parties to the conflict that murder is prohibited under international humanitarian law, and that they must respect the work of humanitarian agencies and refrain from any acts that might jeopardise humanitarian staff or activities."
Rights groups have reported hundreds of abductions and disappearances in recent months after the military and separatist Tigers resumed a two-decade civil war in which nearly 70,000 people have been killed since 1983.
Rajapaksa's office said on Monday the Red Cross volunteer murders were an attempt to damage his and the government's reputation ahead of a meeting with the International Committee of the Red Cross in Geneva later this month.
"The killing of the two Red Cross workers appears to be part of a deliberate campaign to discredit the president and the government and tarnish the image of Sri Lanka vis-a-vis human rights violations," a presidential spokesman said.
He said Rajapaksa had ordered a thorough investigation into the killings.
The international community has voiced repeated concerns about rights abuses blamed on elements of the Sri Lankan military and the Tigers.
Nordic truce monitors suspect military elements were behind the execution-style murder of 17 local staff of aid agency Action Contre la Faim in the island's east last year, the worst attack against humanitarian workers in memory.
