South Korea's acting president Hwang Kyo-ahn will not extend the current special prosecutor's investigation into an influence-peddling scandal that could topple President Park Geun-hye, Hwang's office said on Monday.

Hwang's spokesman Hong Kwon-heui said during a televised briefing that the special prosecution probe had served its purpose and it was in the country's best interests for the investigation to conclude as scheduled on Tuesday.

"After much deliberation the acting president has decided that it would be best for the country's stability to not extend the special investigation and for the prosecutors to take over," Hong said.

The corruption scandal erupted late last year over accusations that Park colluded with a friend, Choi Soon-sil, to pressure big businesses to donate to two foundations set up to back the president’s policy initiatives.

The scandal has led to weekly protests by tens of thousands of Koreans. While some of the protesters support Park, most want her to become South Korea's first democratically elected leader to be thrown from office.

Park, 65, was impeached by parliament in December and has been stripped of her powers while the Constitutional Court decides whether to uphold parliament's impeachment vote, with Hwang acting president in her place.

She cannot be prosecuted while she remains president.

The scandal has also engulfed Samsung Group [SAGR.UL}, South Korea's largest chaebol, or conglomerate. Jay Y. Lee, the head of the smartphones-to-biopharmaceuticals conglomerate, was arrested on Feb. 17.

Park, Choi, Lee and Samsung all deny any wrongdoing.

Hwang, who was appointed prime minister by Park in 2015, is seen as a potential candidate if Park's impeachment is upheld, which would necessitate an election.

However, soon after announcing there would be no extension of the investigation, Hwang found himself dragged into the scandal's fallout when South Korea's two main opposition parties said they would seek his impeachment.

Special prosecution spokesman Lee Kyu-chul said Hwang's decision to decline the investigation team's request for an extension was "very regrettable" and that it had not had enough time to complete its probe, which ultimately targets Park.

"The special prosecutor's office will complete its investigation in a thorough manner," Lee said.

The special prosecution has already indicted former Park aide Kim Ki-choon and former culture minister Cho Yoon-sun.

It had also sought to question Park but was now unlikely to have time.

Should the Constitutional Court uphold parliament's impeachment of Park, South Korea would hold an election within 60 days of the ruling.

The president's office has voiced concern that the special prosecutor's investigation could affect the outcome of any early presidential election.