Defence Ministry said that the suicide attack by a suspected LTTE bomber occurred during a ceremony to mark Eid-e-Milad-ud-Nabi, the birth anniversary of Prophet Mohammad, near the mosque in the Akuresha area in Matara. It is 120 kms away from Colombo
All injured, including Wijesekara, were rushed to a local hospital.
The rebel Tigers have been fighting for a separate homeland for the ethnic Tamil minority in the north and east of the country for a quarter of a century.
In recent weeks, a major Sri Lankan army offensive has inflicted a series of defeats on the Tamil Tiger forces, pushing the rebels into a narrow area of jungle in the north of Sri Lanka.