The Sri Lankan military arrested four suspected Tamil Tiger rebels and discovered weapons during a search of a government-held northern town, the military said on Monday.
The suspected rebels included two women and were arrested late Sunday in Vavuniya, the military said.
T-56 rifles were found in their possession, it said in a statement.
During questioning, the suspected rebels provided information that led to the seizure of four hand grenades and ammunition that had been hidden in a house in Vavuniya, the military said.
Vavuniya, 210 kilometers north of the capital, Colombo, is the last government-held town before rebel territory.
The rebels have fought the government since 1983 to create a separate state for ethnic minority Tamils, accusing the majority Sinhalese of discrimination.
More than 65,000 people were killed in the fighting before a Norwegian-brokered cease-fire was signed in 2002.
The truce has come under increased strain in recent months from escalating violence.