Sepp Blatter has said he will remain as president of FIFA, reiterating that “he had done nothing illegal or improper” after criminal proceedings were opened against him last Friday by the Swiss attorney general.

Blatter returned to work at FIFA headquarters three days after being interrogated there by Swiss investigators.

Blatter is also being investigated by prosecutors over TV rights deals he signed off in 2005 with the now disgraced former Fifa vice-president Jack Warner.