The head of British hygiene product maker Reckitt Benckiser Group plc has offered a "heartfelt" apology over a toxic humidifier disinfectant scandal involving the company's South Korean unit, affirming his priority to address the "unprecedented" tragedy.

Laxman Narasimhan, Reckitt Benckiser's chief executive officer, made the apology in a letter that he sent on Friday to a South Korean independent commission for social disaster investigation after a meeting with its members in Britain.

The scandal, involving the local unit, Oxy Reckitt Benckiser, previously known as Oxy Co., came to light after four pregnant women died of unknown lung problems in 2011. The British firm acquired Oxy Reckitt Benckiser in 2001.

"It is with sincere regret and profound sympathy that I humbly offer my heartfelt apology," he wrote in the letter.

"I appreciate that there is still a long way to go to fully resolve the HS (humidifier sanitizer) issue. This is a priority for me, and I hope together with the commission, we can ensure that all who have suffered can begin the long and necessary healing process," he added.

Members of the commission, dedicated to addressing the scandal and a maritime disaster in 2014, recently visited the RB headquarters and met with company executives.

They have been on a fact-finding mission to uncover the truths behind one of the country's worst consumer product disasters.

After the scandal broke out in 2011, the local authorities launched a probe and concluded that it was caused by polyhexamethylene guanidine, an anti-bacterial agent used in the humidifier cleanser that can be fatal when inhaled in the form of droplets. (Yonhap)