Sri Lankan government has warned the detained ex-army chief Sarath Fonseka against providing "evidence to certain international organisations" on alleged war crimes during the final battle with LTTE as it took strong exception to his remarks that he would "reveal the truth".

"He has reportedly spoken regarding certain things that took place during the war. He also said he is going to provide evidence," Media Minister Lakshman Yapa Abeywardene said.

"If he (Fonseka) is going to give evidence to certain international organisations regarding incidents that have taken place after the war was initiated then I believe that the army has the right to question such a military officer," he told reporters, without naming the global bodies.

Wimal Weerawansa, the chief of the National Freedom Front, a partner of the ruling United People's Freedom Alliance (UPFA), also cautioned Fonseka on the issue.

"Why is a doubt being created in the world. He (Fonseka) was not the one who commanded all the forces," Weerawansa said yesterday, implying that the General was only responsible for army that time as its head, and not for Air Force and Navy.

"The state leader or someone in the political arena can say this. If something has taken place and you are revealing it, then we will make inquires about it. However, for a former army commander, who was there during the war, to make these revelations, it is a betrayal," he said.

Prior to his detention, Fonseka had said on Monday that he was "not going to save anyone who has committed war crimes," according to BBC Sinhala service.