U.N. Secretary-General Ban Ki-moon on Thursday spoke with Sri Lanka's president about the plight of civilians trapped between Tamil rebels and the Sri Lankan army, his spokeswoman said in a statement. “The secretary-general and President [Percy] Rajapaksa of Sri Lanka spoke again today [by telephone] about the deteriorating humanitarian situation in the Vanni region and their shared concerns about the civilians still trapped in the area,” the statement said. Ban “reminds all concerned of their obligations to do all they can to protect civilians, and stresses that civilians should be allowed to leave the affected areas,” the statement added. Sri Lankan forces are battling Liberation Tigers of Tamil Eelam (LTTE) militants who have fought a 25-year war for a separate state for Sri Lanka's Hindu and Christian minorities in the northern part of the country, claiming decades of economic and racial discrimination. There are an estimated 250,000 people trapped between the two sides, the United Nations says.