Colombo  - Sri Lankan security officials discovered a cache of explosives and a suicide kit prepared to kill Sri Lanka's Defence Secretary Gotabhaya Rajapaksa - also the brother of President Mahinda Rajapaksa - in the capital city, police said Monday.

The items were to be used by the Tamil rebels of the Liberation Tigers of Tamil Eelam (LTTE) against the Defence Secretary, police said, without giving information about the time of the planned assassination.

The raid on the arms cache had been based on information gathered by Tamil rebels in custody, they said.

The rebels had intended to stage the killing by distracting the Defence Secretary's convoy with an attack and then detonating a suicide bomb, police said.

The Tamil rebels have been crushed by the military in a major military offensive that ended on May 18. The Defence Secretary escaped a suicide attack by Tamil rebels on December 1, 2006 in the capital.  (dpa)