Updated

Four Christians working for an NGO that helps orphans in Somalia have been beheaded by Islamist extremist group al-Shabaab, according to the human rights watchdog International Christian Concern.

The Christian orphanage workers were reportedly kidnapped on July 27 in the coastal Somali town of Marka, some 56 miles from Mogadishu. Al-Shabaab executed the four when they refused to convert to Islam, according to International Christian Concern.

The reported executions come as residents of the town say the extremist group has been forcibly removing their gold and silver teeth using only rough tools and their hands, possibly to profit from the precious metals.

The group alleges that such artificial teeth are used for fashion and beauty, and therefore violates the strict Islamic religious law they enforce, residents from Marka told Reuters.

Al-Shabaab has been rounding up anyone seen with a gold or silver tooth and taking them to a masked man who then rips out the offending tooth, Reuters reported.

"I never thought al-Shabaab would see my denture as a sin. They took me to their station and removed my silver tooth," a resident named Bashir told Reuters.

"I met several men and women whose dentures were being pulled out by a masked man they called a doctor. The doctor used a pincer or his gloved hand depending on the strength of the tooth," Bashir said.

"As you smile your silver tooth accuses you. I was at a counter with my friend when three armed al-Shabaab ordered me to follow them," he added.

"I am afraid they want to make money from taking all this precious metal."

Al Shabaab officials declined to comment.

Al Shabaab, which means "Youth" in Arabic, is an Al Qaeda-inspired militant group that has been waging a bloody campaign against the country's transitional federal goverment and taken control of large portions of south and central Somalia.

Click here for more on this story from Reuters.