The secret 12-cell prison had markings on the walls that indicated detainees were kept there till 2010 – one year after the nearly three-decade-long war against the LTTE ended, the group had said. UN experts yesterday had said they discovered an illegal detention centre hidden inside a naval base in eastern Sri Lanka. Post-civil war detainees including Tamils were allegedly tortured there, they had said urging the Lankan government to launch a thorough probe. A day after discovery of an illegal detention centre by UN experts in a Sri Lankan naval base where Tamils were allegedly tortured, PMK today demanded the Centre to take steps to send an international team there for a comprehensive probe, the Press Trust of India (PTI) reported.“The Central government should take steps to send an international team to Sri Lanka to carry out a comprehensive probe into past and continuing torture centres and for punishing those responsible for it,” PMK chief Ramadoss said. “This news of a torture centre is not shocking as it is a known truth that several such centres had been in existence all along where Tamils, who raised their voice against Sri Lanka, were tortured,” he alleged in a statement here. “It is not known how many more such torture centres continue to function and about those that had existed,” he said, and reiterated his demand that the Centre should prevail upon Lanka to release all Tamil prisoners.Wrapping up its 10-day official visit to Sri Lanka, a three-member team of the United Nations Working Group on Enforced or Involuntary Disappearances had said it had found an illegal detention centre in the eastern district of Trincomalee where people had been tortured.