What is the ruling on the fast of someone who says, "I am intentionally breaking my fast," during a Ramadan day while fasting?

If by your statement, "I am not fasting," you intended to inform about breaking your intention to fast, then your fast is invalidated, and you must make it up. However, if it was merely a lie and you did not intend to break the fast, then your fast is valid, and you must repent for the lie, as it diminishes the reward of fasting.