South Korean investigators summoned the country's ambassador to France as they widened their inquiry into a corruption scandal involving impeached President Park Geun-hye to include allegations that her administration blacklisted thousands of artists for their political beliefs.

The special prosecution team was planning to question ambassador Mo Chul-min on Thursday over a supposed blacklist of some 9,000 artists who were deemed unfriendly to Park's administration and allegedly denied government support, the AP news agency reported.

Mo served as Park's senior secretary for education and culture in 2013 and 2014.

South Korea's opposition-controlled parliament on December 9 voted to impeach Park, weeks after state prosecutors accused her of colluding with a long-time confidante to extort money and favours from companies and allow the friend to interfere with government affairs.

Park's political turmoil came after years of frustration over her heavy-handed leadership style that critics blamed for setbacks in freedom of speech. Her government pushed to dissolve a leftist party and arrested union leaders, while journalists were pressured with legal and other threats.

Artists have complained about censorship. In 2014, organisers of the Busan International Film Festival clashed with the city's mayor who unsuccessfully tried to block a documentary on a ferry sinking earlier that year that killed more than 300 people, a disaster partially blamed on government incompetence and corruption.

The Mayor of Gwangju recently admitted he was pressured by the government to exclude a painting satirising Park from the city's biannual art fair in 2014.

Dissenting artists 'targeted'

Park's alleged backlist reportedly included some of South Korea's most famous cultural figures, including Oldboy film director Park Chan-wook and poet Ko Un, whose name frequently surfaces in discussions for the Nobel literature prize.

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They were listed for putting their names on statements criticising the government over the 2014 ferry disaster and supporting opposition candidates during presidential and mayoral elections, according to Do Jong-hwan, an opposition MP who broke the list to the media.

Artists' groups say that the allegedly blacklisted individuals, who also include actors, painters, and musicians, have been inexplicably denied financial support available under government programmes and prevented from using state venues.

Former culture minister Yoo Jin-ryong, who stepped down in July 2014, amid a fallout with Park, said in a recent radio interview that the blacklist, which was updated several times before he left, was passed to the ministry through Mo or another presidential secretary.

Investigators step up inquiry

Cho Yoon-sun, the current culture minister who was Park's senior secretary for political affairs from June 2014 to May 2015, denied Yoo's accusation that she was involved, telling MPs she has never even seen the list.

The special prosecution team began investigating the blacklist allegations following a complaint submitted by a group of artists.

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Investigators also summoned Kim Jae-youl, chief of the sports marketing unit of Samsung Group, as they look into allegations that the business giant sponsored the president's jailed friend, Choi Soon-sil, to receive government favours.

Investigators are expected to request a formal arrest warrant for former health minister Moon Hyung-pyo, who they detained on Wednesday.

Moon faces charges that he pressured the National Pension Service to support a controversial merger deal between two Samsung affiliates last year, even though the fund's stake in one of the companies lost an estimated hundreds of millions of dollars in value.

Source: AP news agency