The veteran politician, 84, who is the patriarch of the Chart Thai Pattana Party, was rushed to hospital in the middle of the night on Wednesday.

His family members attempted to use an inhaler to help him breath but failed.

The dean of Siriraj’s medical faculty, Dr Prasit Wattanapa, said that the politician’s condition was still critical.

He said Banharn needed medication for his heart and for broncho-dilation to regain normal respiration.

“Multiple medications are involved in his treatment, making it difficult to say whether he was conscious or unconscious. He will still need close medical attention,” Prasit said.

Banharn’s colleagues from Chart Thai Pattana, Nikorn Chamnong and Somsak Prissananantakul, said the former prime minister has long suffered from chronic asthma and usually used an inhaler twice a day. The attack was possibly because of the weather change, they added.

They said Banharn was almost fully recovered.

Banharn is popularly known for representing his home province Suphan Buri, leading it to its rapid growth and development.

Many schools and facilities in the province have been named after him and his wife, Jamsai Silapa-archa, such as Banharn Jamsai School.