TIMELINE - Sri Lanka's 25-year civil war

April 20 - Sri Lanka gives the rebels 24 hours to surrender as tens of thousands of civilians flee battle zone.

April 26 - Tigers declare a unilateral cease-fire. Sri Lankan government dismisses cease-fire and says they must surrender.

April 27 - Sri Lankan government says it ceases combat operations with heavy weapons and operations will be confined to using only small arms and rescuing civilians trapped in the war zone.

(Writing by Ranga Sirilal; Editing by Jerry Norton)