Seoul, Mar 11 (IANS): Jae-yong, the imprisoned de facto leader of Samsung Group, is under investigation over an allegation that he took anesthesia drug propofol shots illegally, police said on Thursday.

Propofol is a highly regulated drug in South Korea that the country's Ministry of Food and Drug Safety issued standards to prevent its misuse and abuse.

The ministry issued a notice last September to set standards for the use of narcotic drugs propofol and zolpidem, saying propofol is a "psychotropic drug used to induce and maintain the general anesthetic state."

The Gyeonggi Nambu Police Agency said they were looking into the accusation made against Lee, vice chairman of Samsung Electronics, that he illegally used the anesthesia drug at a plastic surgery clinic in Seoul last year, but refused to provide further details on the ongoing case, reports Yonhap news agency.

The police are said to have visited Lee, who is imprisoned in the Seoul Detention Center in Uiwang, south of the capital, last month to take a hair sample from him for drug testing.

Lee is currently serving a two-and-a-half-year prison term for bribing impeached former President Park Geun-hye and her longtime friend Choi Soon-sil to win government support for a smooth father-to-son transfer of managerial power at Samsung.

Samsung said that Lee only took propofol shots for medical purposes and that the police have not corroborated the allegation against him, reports Yonhap news agency.

Early last year, a similar accusation was filed against Lee with the Anti-Corruption and Civil Rights Commission that he regularly used propofol at another plastic surgery clinic in Seoul.

The case has been referred to the Supreme Prosecutors Office.

Lee also denied the allegation at that time and requested the case to be reviewed by an independent committee consisting of outside experts to see whether the prosecution's investigation is legitimate.