Kerala Chief Minister Pinarayi Vijayan left Sunday for the US for medical treatment, sources said.
He left for treatment at Mayo Clinic and was expected to be back after three weeks, they said.
He was supposed to have left for the US on Monday.
During his absence, Industries Minister EP Jayarajan would receive donations towards the Chief Minister's Disaster Relief Fund (CMDRF) at the Chief Minister's office in Thiruvananthapuram, a release said.
Mr Vijayan, 73, had on Saturday called on Governor Justice (Retd) P Sathasivam and briefed him about his trip abroad for treatment.
The chief minister had also updated the governor about the steps initiated by the government for rebuilding Kerala and for rehabilitation of the flood-affected people.
Mr Vijayan was originally scheduled to go for treatment on August 19 and return by the middle of this month.
He postponed the trip due to the unexpected floods that ravaged the state and claimed more than 400 lives.
The chief minister had undergone a routine annual medical check-up at Apollo Hospitals at Chennai on March 3.