The Corruption Investigation Office for High-ranking Officials(CIO) expressed regret over allegations it made an inquiry into the telecommunication records of politicians, journalists and members of the general public.

The CIO issued a statement on Friday, saying it regrets creating public controversy after following inadvisable investigative practices of the past without sufficient self-examination.

The agency said it will call in outside experts in an independent review before unveiling measures to improve its investigative practices.

It also pledged to ensure that its investigative procedures don't infringe upon constitutional rights or trigger public misunderstanding in the future.

The agency, however, explained that checking the telecommunication records were inevitable, while seeking understanding about difficulties in revealing details of ongoing investigations.