| Conflict: | Thandikulam-Omanthai offensive |
| Partof: | the Sri Lankan civil war, Operation Jayasikurui |
| Date: | 10 June 1997 - 25 June 1997 |
| Place: | Sri Lanka |
| Result: | Tamil Tiger victory |
| Combatant1: | Military of Sri Lanka |
| Combatant2: | Liberation Tigers of Tamil Eelam |
| Casualties1: | 700 killed 1,500 wounded |
| Casualties2: | 165 killed |
The Thandikulam–Omanthai offensive was a battle for the control of the towns of Thandikulam and Omanthai in Sri Lanka in June 1997.
The battle began on 10 June 1997, when LTTE fighters attacked the garrison at Thandikulam. They destroyed the bridge on the edge of town so no reinforcements could arrive. While the fighting was raging an arms dump was hit by a rocket, causing a huge explosion that resulted in many casualties. Another dump was also hit shortly after and caused the same result. Helicopter gunships were sent to try to assist the besieged soldiers, but one of them was badly damaged.[1] Finally the town fell and the Tigers held it for two days, taking everything they could.
The LTTE attacked Omanthai thirteen days later. To get to Omanthai they had to go through Periyamadu, where 250 Sri Lankan soldiers were stationed. As the Tigers attacked, all of the soldiers deserted their bunkers and left a gap over long in the camp's perimeter. The Tigers took full advantage of the gap by swarming into Periyamadu and pushing their way deeper and deeper into SLA territory. Within minutes the Tigers had reached the main military base at Omanthai and headed straight for the artillery cannons. In heavy hand-to-hand combat, the Tigers took Omanthai, capturing six artillery pieces as well as several armoured vehicles.