The Ministry has been in touch with Gudelj's family and with Croatian journalists reporting from Thailand, said Vinko Ljubicic, who is in charge of Croatian diplomatic missions and consular offices.
Gudelj left Duesseldorf for Bangkok on December 24.
Ljubicic said that Croatian nationals Kristina Pucko and Jurica Saha, who had been hospitalised in Sri Lanka, arrived in Zagreb on Sunday.
Pucko suffered an injury to her leg in a tsunami and had to undergo an operation in Colombo.
There were 80 Croatian nationals in Southeast Asia last Sunday when the region was devastated by tidal waves known as tsunami, triggered by a magnitude 9.0 earthquake that struck the Indian Ocean.
The first Croatian victim of a tsunami is three-year-old Vivian Slot, granddaughter of the head of Zagreb University, Helena Jasna Mencer.
According to the latest reports, more than 130,000 people were killed in the disaster. It is feared that the death toll could exceed 200,000.