The millions of pieces of ammunition includes 7.62 millimetre submachine gun bullets, hand grenades, smoke bombs and shells.
Speaking to journalists after a government meeting, Kuehnl told journalists that sending the ammunition to Afghanistan was financially more advantageous for the state than either storing or dismantling it.
The United States has promised to ensure the ammunition's transport to Afghanistan.
The state would have had to spend 50 million koruna (1.6 million euros, two million dollars) annually storing the redundant ammunition while its liquidation would cost around 350 million koruna, he said.
"We have therefore saved money and in addition, have helped to stabilise the region," he added.
The Czech military is currently disposing of redundant ammunition and has hired companies to destroy 39,000 tonnes of equipment by mid-2007.
Another 27,000 tonnes is due to be donated or possibly sold.