Tamil rebels began fighting for an independent homeland in 1983.
It is not clear what effect their presence in a coalition government would have on the island nation's stalled peace talks with Tamil rebels.
Dozens of civilians have been killed during fighting between government troops and separatist Tamil rebels.
It was closed for violating guidelines about reporting on the war against separatist Tamil rebels.
The raid left at least 19 people dead, including 14 Tamil rebels, two army commandos and three air force personnel.
A year ago there was one ethnic insurgency, that of Tamil rebels fighting for an independent state.
The daughter's years in office have been dominated by her as-yet-fruitless efforts to end a 17-year-old war with separatist Tamil rebels.
Tamil rebels are believed to be responsible for the mortar attack.
Tamil rebels took up arms in 1983 to fight alleged discrimination by the Sinhalese majority.
She said that the body of a Tamil rebel was recovered and that at least 10 more rebels were believed killed.