OpenGL ES 2.0 on iOS non-square texture gets distorted when rendered - iphone

Question

I am working on OpenGL ES 2.0 on iOS and I have this...
A texture (T1) with some image (size 1024x768).
An off screen FBO (FBO1) associated texture T1 so that I can render something into T1.
Another texture (T2) of the same size.
Another FBO (FBO2) associated with T2. (I will render to texture T2 with it).
Now in a loop, I render the content of T1 into FBO2 (so T1 gets transferred to T2) and then render T2 into FBO1 (T2 gets transferred back into T1).
After couple of iterations (just 7-8), the original image which was loaded to T1 gets severely distorted/blurred (as if it did a horizontal blur).
But if I do the same thing with a square image (need not be power of two), the image remains clear.
Here is the code that I use to create the texture..
GLuint texture = 0;
glGenTextures(1, &texture);
glBindTexture(GL_TEXTURE_2D, texture);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, buffer);
And here is the code I use to create the FBO...
glGenFramebuffers(1, &targetFBO);
glBindFramebuffer(GL_FRAMEBUFFER, targetFBO);
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, texture, 0);
My shaders are the most basic ones, just renders the texture into gl_FragColor.
Here is my render Objective-C code...
- (void) draw {
GLfloat textureCoordinates[] = {
0.0f, 0.0f,
1.0f, 0.0f,
0.0f, 1.0f,
1.0f, 1.0f,
};
GLfloat imageVertices[] = {
-1.0f, -1.0f,
1.0f, -1.0f,
-1.0f, 1.0f,
1.0f, 1.0f,
};
glViewport(0, 0, targetWidth, targetHeight);
glBindFramebuffer(GL_FRAMEBUFFER, targetFBO);
glUseProgram(program);
glActiveTexture(GL_TEXTURE2);
glBindTexture(GL_TEXTURE_2D, textureID);
glUniform1i(inputTextureLocation, 2);
glDisable(GL_BLEND);
glVertexAttribPointer(positionLocation, 2, GL_FLOAT, 0, 0, imageVertices);
glVertexAttribPointer(inputTextureCoordinateLocation, 2, GL_FLOAT, 0, 0, textureCoordinates);
// Clear the screen
glClearColor(0.0, 0.0, 0.0, 0.0);
glClear(GL_COLOR_BUFFER_BIT);
glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
}
And my vertex shader...
attribute vec4 position;
attribute vec4 inputTextureCoordinate;
varying vec2 textureCoordinate;
void main()
{
gl_Position = position;
textureCoordinate = inputTextureCoordinate.xy;
}
Fragment shader...
varying highp vec2 textureCoordinate;
uniform sampler2D inputTexture;
void main()
{
gl_FragColor = texture2D(inputTexture, textureCoordinate);
}
Original image...
Distorted image ...
How do I avoid blurring on non-square textures?
Edit: The problem is actually with No-Power-of-Two textures. Not just non-square. I am not able to find a solution, so I am going with POT textures.