SEOUL, March 24 (Reuters) - Former South Korean President Park Geun-hye left hospital on Thursday three months after she was released from prison where she spent nearly five years following a conviction on corruption charges.

Park, 70, became the country's first democratically elected leader to be forced from office when the Constitutional Court upheld a parliament vote in 2017 to impeach her over a scandal that also landed the chiefs of two conglomerates, Samsung and Lotte, in jail.

The Supreme Court last year upheld Park's sentence of 20 years in prison for colluding with a friend, who was also jailed, to receive millions of dollars from the companies, mostly to fund her friend's family and non-profit groups.

Outgoing President Moon Jae-in granted a special pardon to Park in December, citing her deteriorating health and his hopes to move past the "unfortunate history" and promote national unity.

Park smiled as she left the Samsung Medical Centre in Seoul dressed in a dark navy coat and holding a purse.

"I offer my greetings after five years," she said. "I have recovered a lot thanks to your concerns."

She declined to answer reporters' questions.

Some 40 supporters cheered as Park, the daughter of former dictator Park Chung-hee, appeared. Dozens of officials who served in her administration and her conservative political party also gathered to offer their best wishes.

Park visited her father's grave before heading to a new residence in the southeastern city of Daegu.

Park's imprisonment divided a country in which old Cold War rivalry between right and left still shapes politics.

Right-wing groups supporting Park had staged weekly rallies to denounce Moon and his liberal administration until COVID-19 distancing rules limited protests.

Park's release comes days after a presidential election won by conservative candidate Yoon Suk-yeol.

President-elect Yoon, who was in involved in the investigation of the corruption charges against Park when he served as prosecutor-general, said during the election campaign that he was sorry about what happened to her.

On Thursday, he said he hoped to meet her and would invite her to his inauguration in May.

Moon's office said he had sent Park an orchid and wished her well.