Imprisoned former Sri Lankan armed forces chief Gen Sarath Fonseka has denied being a liar.
He also denied committing treason when speaking of the possibility of war crimes being committed during fighting against Tamil Tiger rebels.
Gen Fonseka was interviewed by the BBC's Sinhala service a day after the defence secretary described him as a liar and threatened him with execution.
Meanwhile a report says Mr Rajapaksa has been clarifying his own remarks.
Gen Fonseka spoke to the BBC Sinhala service on the telephone while attending parliament, which he can do since being elected as an MP two months ago.
"How can it be?" he asked.
"If I cover up, if I hush up things, if I don't tell the truth fully I will become a traitor.
"If I know anything about war crimes my duty is to expose. That is what we are supposed to do as a responsible citizen, as a responsible ex-army officer, or as a responsible MP - we are not supposed to cover up anything."
Gen Fonseka accused Defence Secretary Gotabhaya Rajapaksa of "throwing mud" after Mr Rajapaksa told the BBC's HARDtalk programme that the general was a liar and might be hanged for - as he put it - betraying the country.
That was in response to Gen Fonseka saying he would be prepared to testify before any independent investigation of alleged breaches of humanitarian law during the war against the Tamil Tigers - even though he himself was army commander at that time.
Gotabhaya Rajapaksa has meanwhile sought to clarify his remarks.
He told a local news website that what he meant was that if the general was found guilty of treason, he could be sentenced to death.
Gen Fonseka is currently undergoing two military trials and one civilian one but in none of them has he been charged with treason.
Meanwhile about 150 of his supporters and relatives have held a candle-lit vigil to mark exactly four months since the government dragged him forcibly into detention.