Sri Lanka rejected a deal on Sunday brokered by Norway with Tamil rebels to lift a water blockade, saying access to the site by its engineers was non-negotiable. Government spokesman Keheliya Rambukwella said they were not involved in Norway's talks with the Liberation Tigers of Tamil Eelam (LTTE) that led to the guerrillas announcing they will open a sluice gate closed in late July. "Water should not be a negotiating tool," Rambukwella told AFP. "We don't want terrorists to come and open the water way. They must simply allow irrigation engineers to do it, otherwise we will open it anyway," he said.The LTTE, in talks with Oslo's top special envoy Jon Hanssen-Bauer, agreed on Sunday to end the dispute by releasing water to around 15,000 farming families. Tiger political wing leader S P Thamilselvan said the Tigers would unblock a sluice gate in the east - a blockage that plunged the island into a fresh bout of civil war - if the government agreed to their demands. "Our leader has agreed to open the sluice on humanitarian grounds," Thamilselvan told reporters in the northern rebel stronghold of Kilinochchi.