The head of South Korea's Samsung Group, Jay Y Lee, may be in a jail cell but he is allowed plenty of visitors.

This may allow him to play a key role in corporate decisions even if he is not running the conglomerate like he did before. 

Lee, who did not attend last Thursday's preparatory hearing for his trial on bribery, embezzlement and other charges, is kept well away from other inmates at the Seoul Detention Centre. 

Some, such as top former presidential advisors, are also defendants in the corruption scandal that led to the removal from office of South Korean President Park Geun-hye on Friday. 

Under South Korean regulations, though, Lee can meet any of his army of lawyers without time limits and as often as he wants during business hours from Monday to Saturday. 

One of those lawyers told the first day of what special prosecutors described as potentially "the trial of the century" that Lee denies all charges against him. 

Lee, like others in detention centres awaiting trial, is also entitled to one 30-minute visit per day from someone else, including executives from one of Samsung’s affiliates, or at least 12 hours of such meetings a month.

At the discretion of the warden of the detention centre, he could have additional special meetings in a visiting room that does not have partitions, allowing detainees to review documents and receive phone calls. 

South Korean media have photographed former Samsung Group Vice Chairman Choi Gee-sung and Samsung Electronics President Rhee In-yong visiting Lee following his arrest last month. 

Samsung declined to confirm those visits or comment on the level of Lee's involvement in management affairs since he was detained.

 It did say that he is meeting regularly with his defence team, though declined to be more specific. 

"Mr Lee's priority is preparing the legal defense so the truth can be revealed in future court proceedings," the company said in a statement. 

Samsung has not named a replacement for Lee, who company insiders say did not manage day-to-day affairs but was instead acting as the key decision maker on major initiatives such as new investments, acquisitions, personnel decisions and restructuring. 

"There is no plan B," said an executive at a Samsung affiliate, who declined to be identified as he was not authorised to speak publicly on the matter. 

"We believe the vice chairman will be proven innocent, and if he walks free after the first trial there's no reason to talk about alternatives." 

Samsung Group has disbanded its corporate strategy office, the conglomerate's nerve centre controlled by Lee and his lieutenant Choi Gee-sung, who is also a defendant in the case.

It has also been moving in the past year to give more power over decisions to the boards of its affiliates such as Samsung Electronics.

While Lee will not have access to a computer in his 6.56 square meter (71 square foot) cell, he can view documents during those meetings with his lawyers and Samsung executives. 

Lee is not allowed to take documents back to his cell. 

He can also make phone calls with permission of the warden, but calls can be recorded or listened to by the authorities, according to South Korean correctional rules. 

Lee may remain at the detention centre until at least September should the case end up in the Supreme Court and he does not seek bail. Samsung said Lee has not decided yet whether to seek bail. 

Despite the access to attorneys and executives, it is not easy for business leaders to participate fully in company affairs once they are in jail, according to those who have had previous experience of such dealings.