Islamic State said it had killed a Norwegian and a Chinese captive, showing what appeared to be pictures of the dead men under a banner reading "Executed" in the latest edition of its English language magazine, Reuters reports.

It did not give any details in the online Dabiq magazine, published on Wednesday, November 18, about how, when or where the men were killed.

Norway's Prime Minister Erna Solberg told a news conference in Oslo that the Norwegian man, named by the foreign ministry as Ole Johan Grimsgaard-Ofstad, had most likely been killed.

In September, Solberg said a Norwegian had been held hostage in Syria since January and was believed to be in the hands of Islamic State, which has seized large swathes of Syria and Iraq.

"We condemn the killing," Solberg said, adding the government was still seeking further verification.

Chinese Foreign Ministry spokesman Hong Lei said Beijing was "greatly shocked" by the reports, but was still seeking verification of the execution of the Chinese national.

In a statement on the ministry's website, Hong said the government had been trying to secure the release of the hostage. China's Foreign Ministry said in September that one of its citizens appeared to be in Islamic State captivity.

The militant group had previously identified the Chinese man as Fan Jinghui and said he was a 50-year-old freelance consultant from Beijing, but the Chinese government has not confirmed his identity.