(adds TV and PIX to slugline, adds details on relationship between patients in paragraphs 3-4)
BANGKOK, Feb 26 (Reuters) - Thailand reported three new cases of a coronavirus on Wednesday, taking total infections to 40, health ministry officials said, criticizing patients for not disclosing their travel history.
Health Minister Anutin Charnvirakul asked the Thai public to avoid travelling to affected countries and called on airlines to refrain from luring travelers with promotions.
Two of the new patients, all of whom were Thai nationals, had returned from vacation in Japan's northern island of Hokkaido and came into contact with the third patient, their 8-year old grandson, said Sukhum Kanchanapimai, permanent secretary at the Public Health Ministry.
The grandfather had not disclosed his travel history when he first sought medical attention and risked becoming a super-spreader, an incident of large transmission from a single source, Anutin said.
"We have to criticize this case ... it creates a lot of trouble for us," Anutin said.
The patient came to the hospital on Feb. 23, but did not disclose his travel history until the next day, B Care Medical Center said in a statement.
The patient came into contact with 30 medical personnel at the hospital, who later tested negative for the virus and are in self-quarantine at home, the statement said.
Passengers, cabin crew and students in the boy's class were all being tested, officials said.
The boy's school has been closed for 14 days and will be cleaned, a statement from the Don Mueng District Office said.
A Thanachart-TMB bank also announced it would close its branch in the area for disinfection after an employee's relative was reported to have the virus.
The branch's workers have tested negative for the virus, but were asked to stay home for 14 days, it said.
Public Health Ministry officials will be prohibited from traveling to risky countries. If travel is required, personnel are required to self-quarantine for 14 days, Sukhum said.
At-risk countries include China, Macau, Hong Kong, Taiwan, South Korea, Singapore, Italy, Iran and Japan.
"For the airlines, please reduce promotions," Anutin said.
"Even though tickets are cheap, it could be your last holiday."
National carrier Thai Airways Pcl said its executives took pay cuts to reduce costs amid the fall-off in passenger travel. (Reporting by Chayut Setboonsarng, Panarat Thepgumpanat and Panu Wongcha-um; Editing by Clarence Fernandez & Simon Cameron-Moore)