I know it is very common these days to associate Chakras with Buddhist meditation, but I couldn't find anything that supports that in the suttas. (I haven't read all suttas)
Did the Buddha himself taught about Chakras or has it been incorporated later in some parts of the world?
There is nothing supernatural about chakras. They are psychosomatic phenomena; they exist only in the subjective world of a person. That's why you can't photograph a chakra, or measure its "field intensity" with some kind of device.
If you inspect your subtle tactile perceptions, you will surely notice feelings in and around your chest, stomach, forehead, eyes, hands, wrists, feet etc. Subjectively, these feelings are not located on the surface of, or inside the body, but rather "in the air" around it. They are not produced by a contact with an external object, and they are not as sharp as itching or pain. What are they then?
Chakras are somatic projections of our emotional state onto the internal map of the body. They are indicators of what goes on inside our brains, below the threshold of awareness. Some of the emotions most often accompanied by chakra sensations are worry, urge, longing, resentment, irritation but also the positive ones e.g. love, fondness.
In Chinese Mahayana, Buddhism is often taught in combination with Tai-Chi, Qi-Gong, and other forms of "energy management" exercises focused on developing one's psychosomatic skills. The Chinese (also Korean, Vietnamese, etc.) recognize three main chakras: lower dantian (lower abdomen), middle dantian (chest) and upper dantian (head). The Indians recognize more chakras, but if you think about it, these are just alternative ways to emphasize some of the most important locations in person's subjective space.
Even though Buddha did not mention chakras directly, his various mindfulness practices are essentially chakra exercises. Specifically, kayagata-sati (mindfulness rooted in the body) involves paying constant attention to feelings around throat, chest, solar plexus, lower abdomen, and feet. Similarly, anapana-sati (mindfulness of breathing) involves paying attention to the diaphragm, esp. the sensations experienced around the moment when the breath reverses its direction.
But to answer your question directly, no, Buddha of Pali Canon did not speak about chakras, these and other practices (yoga, tantra) were incorporated later, as people realized their affinity with Buddhism's goal and methods.
As far a I know only the Vajrayana school of Buddhism includes chakras within it's teaching. This being a school heavily influenced by Tantric/Yoga practises, so it's mostly practised in Tibet, Nepal, Bhutan and Mongolia.
It's not a part of the other schools and doesn't feature in the suttas.
There are indirect references although this concept doesn't exist in Theravada Buddhism.
E.g. in Anapana many Theravada traditions teach to keep your attention around the mouth or base of the nose and upper lip (Ledi Sayadaw and student's interpretations). This area is pretty sensitive when you start looking deeply into the touch sensations. There is also some advice on other points like the chest, pallet, breast bone (Thai Forest tradition as taught by Ajaan Lee Dhammadharo) or stomach (Mahaisi Sayadaw Linage, Thai Forest Tradition).
Thai Forest Tradition (as taught by Ajaan Lee Dhammadharo) focuses different nerve centers, much more than any other Theravada traditions. The interpretation here is not they are chakras put nerve centers which help anchor your concentration. May of these point bear physical proximity to where chakras are.
Yes. The Buddha mentions all these things as the "fire element."
He did not draw attention to these things because the kundalini phenomenon, which purifies your chakras is aggravated when the user's attention is drawn to it.
Also there is a tremendous amount of other cultivation and real-life concepts he had to discuss then go into these concepts all day.
Thus, the Buddha ignored the concept of chi channels because it is best for monks to do so.
Nowadays, you cannot ignore such a concept because our minds are more filled with information. You will subconsciously think about it one way or another and affect your experience.
Which is why you now need the information to ignore the concept.
I refer you to Master Huai-Chin Nan's book Tao & Longevity for a longer, fuller explanation of chi channels, chakras, longevity, and immortality (and then he tells you to ignore all of it if you want to achieve it).
