About 140,000 owners of the Galaxy Note 7 smartphones in South Korea have not returned their devices, an industry source said Tuesday, complicating efforts by Samsung Electronics Co. to end the recall program for the phablet by the end of this year.

More than three months after conducting a global recall of the Note 7 over a safety risk, the retrieval rate in South Korea stood at 85 percent. Given that some 950,000 Note 7s were actually sold in South Korea, the remaining 15 percent still pose a safety risk. 

In the US market, more than 93 percent of Note 7s sold have been returned, Samsung said in a statement released earlier this week.

"To further increase participation, a software update will be released starting Dec. 19 and will be distributed within 30 days.

This software update will prevent US Galaxy Note 7 devices from charging and will eliminate their ability to work as mobile devices," Samsung said.

In South Korea, Samsung is unlikely to take the same measure due to a low retrieval rate, according to the industry source.

"If Samsung prevents the Galaxy Note 7s from charging, it will cause a strong backlash from owners," the industry source said on the condition of anonymity.

Samsung is expected to increase the retrieval rate in South Korea as it has extended an exchange and refund program for the Note 7 to the end of this month.

Depending on the rate of returns, Samsung is likely to begin discussions with domestic mobile carriers about how and when to end the recall program.

An official at a local mobile carrier said it will be difficult for Samsung to end the recall program in South Korea by the end of this year.

As part of efforts to increase the retrieval rate in South Korea, Samsung is said to have been considering allowing owners to charge their Note 7 batteries to 15 percent, according to the source. (Yonhap)