Park Geun-hye, the impeached president of South Korea, has appeared in public for the first time in more than a month to deny charges of wrongdoing and say corruption allegations against her are a “fabrication and falsehood”.

Park said she was set up over claims that she ordered the government to support a merger in 2015 of two affiliates of Samsung Group, a deal that has become central to a corruption investigation.

“It’s completely framed,” she was quoted as saying by local media, without elaborating.

Park is accused of giving favours to major companies in return for financial contributions to entities controlled by her close friend Choi Soon-sil.

On Sunday, Park denied that Choi was allowed undue and wide-reaching influence over state affairs.

In a hastily arranged briefing over tea, the president met South Korean media in her first public event since being impeached by parliament on 9 December. Constitutional court judges have up to six months from this date to uphold the impeachment or reinstate her.

Her last public appearance had been on 29 November, when she offered to step down if parliament could agree on a way for her to leave office.

Opposition parties rejected this and led a motion to impeach the president by a wide margin, joined by some members of her Saenuri party. The court is set to begin hearing arguments from both sides.

Park has previously denied wrongdoing but apologised for carelessness in her ties with Choi, a friend for four decades, who has also denied wrongdoing. Choi is being detained while on trial.

On Sunday, Park said the decision by South Korea’s national pension fund to support a merger of Cheil Industries and Samsung C&T Corporation was “a just policy decision” in the national interest that was supported by many brokerage firms at the time.

“I did not have an iota of thinking to help anyone and the thought never crossed my mind,” Park said. “This is not the place to tell you all the details, but what I can clearly say now is that I did nothing whatsoever to favour anyone or collude with anyone to do that.”

The deal has been criticised by some investors for strengthening the Samsung founding family’s control of the country’s biggest conglomerate at the expense of other shareholders.

The National Pension Service, which had 545tn won (£366bn) under management at the end of September and was a major shareholder in the affiliates, voted in favour of the merger without calling in an external committee that sometimes advises it on difficult votes.

Park, 64, is accused of colluding with Choi to pressure large businesses including Samsung to make contributions to non-profit foundations that support presidential initiatives.

Over the past few months, hundreds of thousands of protesters have demanded that Park resign immediately from office, but she has indicated through her lawyers that she will fight her impeachment in court.

Park also addressed accusations of negligence in her handling of the Sewol ferry disaster in April 2014 that killed more than 300 passengers, mostly schoolchildren.

At the time, she was criticised for mishandling the rescue efforts and questioned over her whereabouts during the seven hours between the first report of the incident and her appearance in the government’s emergency room.

The president denied allegations that she failed to pay closer attention to the rescue operation because she was receiving a cosmetic procedure. “That is not possible even by common sense,” she said.