South Korean President Yoon Suk-yeol has offered an apology for causing concern amid allegations that he and his wife meddled in candidate nominations in past elections. But he denied doing anything unlawful.

Yoon spoke at a news conference on Thursday ahead of the midpoint of his five-year term. His remarks came as his approval rating dipped below 20 percent for the first time since he took office in 2022.

The president faces criticism from the opposition over suspicions that he and first lady Kim Keon-hee wrongfully interfered in the ruling party's candidate nomination process in past elections.

The head of the ruling party also called for Yoon's apology.

Offering an apology, Yoon said he is to blame for everything due to his carelessness and lack of diligence. But he said he has done nothing unlawful and has nothing to hide.

The president also said his wife should have acted with prudence, and it was wrong to have caused concern to the public.

A Gallup Korea poll that was announced on November 1 showed Yoon's approval rating sagged to 19 percent.

The president is expected to have a tough time steering his administration for the rest of his tenure as his ruling People Power Party suffered a major defeat in the April general election.