Sections of the Turkish army have officially declared a coup, saying they have "taken control of the country" as major bridges and Istanbul's main airport were closed and fighter jets were seen in the skies.

President Recep Tayyip Erdogan in a phone call to broadcaster CNN Turk said he remained the president of the country and the head of the army and called for people to take to the streets against the coup.

A government official told the DPA news agency that the president was in a "secure location", giving no further details.