UNITED NATIONS, May 10 (Reuters) - Sri Lanka’s president said the country’s separatist rebels have so far refused to put "core" issues on the agenda at expected June talks in Bangkok, aimed at ending one of Asia’s longest-running civil wars.

President Chandrika Kumaratunga, attending a U.N. special session on children, told a news conference on Thursday the rebel Tamil Tigers wanted to form an interim council in areas they hold but rejected talks on alternatives to a separate state.

Norway, after brokering a fragile cease-fire in February, is organizing direct talks with the government of the island nation off the southern tip of India and the Liberation Tigers of Tamil Eelam, which have been fighting since 1983 for an independent Tamil homeland. The war has cost 64,000 lives.

"They have not yet agreed to talk in Bangkok or anywhere about the main issues" Kumaratunga said. "What do you do if we are not going to have a separate state? What is an alternative?

"We tried on two occasions and could not bring them to talk about the core issues so one is not hugely elated," she said.

Velupilla Prabhakaran, the Tigers’ leader, wants an interim council to administer a homeland in the north and east of the country where the 3.2 million Tamils are in the majority. They accuse the country’s Sinhalese, who comprise 70 percent of Sri Lanka’s 18 million people, of discriminating against them.

Kumaratunga said "constitutional arrangements" have been discussed among all parliamentary parties but the rebels "have not even agreed to talk about it."

"That is skirting around the bush as they have for many years with various governments so one is apprehensive," she said. The president who comes from a different party than Prime Minister Ranil Wickremesinghe has been skeptical about chances for peace and has criticized the cease-fire as a threat to national security.

She said the Tigers, which arguably hold the world’s worst records in suicide bombings, had not stopped their forced recruitment of youngsters despite promises to the contrary to Olara Otunnu, the U.N. official for children in war zones.

"Children are grabbed when they go to school or they are walking about and they are finally converted and transformed into human bombs who destroy themselves and hundreds of others," Kumaratunga said.

She estimated that at least 2,000 of the rebel army of some 6,000 were children under 18 years of age. She said it appeared recruitment of child soldiers had slowed down but had not stopped over the past month.