Bonus shares + Existing shares sell and LT or ST tax?

Respected Members,

A company has alloted me some bonus shares. Let's say I already have 500 for past 3 years and now 500 are alloted now.

So in one transaction if I sell all 1000 now, how is the tax implication from Long Term and Short Term gains pespective?

I mean it will be one transaction by the share broker but if I correctly understand the gain from old 500 shares is LT & other 500 is ST? Correct me if I am wrong.

Please advice.

Thanks and regards.