"He is now, at this moment, in hospital," Blatter's spokesman Klaus Stoehlker told news agency AFP by phone. "He is preparing to leave on Monday and will be back on the job on Tuesday."
Stoehlker added that 79-year-old Blatter had "regained his good humour" and has vowed to persist with "his fight against the (Fifa) ethics committee" which suspended him for 90 days over corruption allegations.
Blatter, long the most powerful man in football, suffered a medical incident last weekend and had been placed under medical observation from his home.
Blatter's daughter Corinne has said that her father had been forced to cancel all of his appointments up to November 15th.
Stoehlker previously said the stress-related medical incident had been brought on by the pressure the embattled Swiss national has faced in recent weeks.
Blatter has been at the centre of the worst scandal to ever hit world football. Swiss prosecutors opened a criminal case against him in September, an announcement that led to his suspension from Fifa.
Before he was suspended, Blatter, who has been in charge of Fifa since 1998, had said he would step down on February 26th, next year, when a Fifa congress elects a new president.
Figueredo agrees to extradition
Separately, former Fifa vice president Eugenio Figueredo, who served under Blatter, agreed to be extradited from Switzerland to his home country of Uruguay, where he faces corruption charges.
But the extradition could be challenged by the United States justice department, which charged Figueredo as part of its sweeping indictments in May.
The Swiss justice ministry (FOJ) has approved Figueredo's extradition to both the United States and Uruguay.
"It will be for the US authorities to state whether or not they agree to Uruguay being given priority. If the US authorities do not agree, the issue will be decided by the FOJ," a statement from FOJ spokesman Folco Galli said.
Figueredo, 83 and a former vice-president of the South American Football Confederation (Conmebol), was charged by the US with using his influence to solicit millions of dollars worth of bribes.
While Figueredo was detained in Switzerland, Uruguayan authorities launched a separate investigation and have since charged him with abusing his office.
Figueredo continues to fight against extradition to the United States.