How to Stop Loading in As3 & As2

In Stage having two buttons btn, btn1 movieClips. when i click btn load a  test.swf file . if the swf file size is too heavy i want to stop the loading,  with usind btn1 click. How i can stop the loading . Please provide the solution  in AS2 & AS3

var ldr:Loader;
btn.addEventListener(MouseEvent.CLICK,statrLoading);
btn2.addEventListener(MouseEvent.CLICK,stopLoading);
function statrLoading(e:MouseEvent) {
    loadStrt();
}
function stopLoading(e:MouseEvent) {

    ldr.close();
    // it is not Working
}
function loadStrt() {

    ldr = new Loader();

    var url:String = "test.swf";
    var urlReq:URLRequest = new URLRequest(url);
    ldr.contentLoaderInfo.addEventListener(ProgressEvent.PROGRESS,Onprogress);
    ldr.load(urlReq);
    addChildAt(ldr,1);
}
function Onprogress(e:ProgressEvent) {
    txt.text=e.bytesLoaded+" of "+e.bytesTotal;

}