Four Chinese workers, who were abducted last week in Sudan's Darfur region, have been released and are reported to be in good health. The Chinese Embassy in Khartoum said the Chinese workers have been handed to the United Nations-African Union Mission in Darfur. Despite the release, embassy officials has since advised Chinese companies and Chinese nationals in Sudan to exercise maximum caution. North Darfur state's authorities earlier arrested a number of people belonging to a rebel faction responsible for the kidnapping. Efforts are also continuing to ensure the release of five Sudanese who were abducted along with the four Chinese last Saturday. A British and a Norwegian have been killed reportedly in an attack by Islamist militants on a gas facility in Algeria. At least 20 more - including US, French, British, Norwegian and Japanese citizens - are being held at the facility near Amenas. The raid, claimed by an al Qaeda affiliate, came after Islamists had vowed to retaliate for France's military intervention in Mali, where its forces have been in action against al Qaeda-linked militants since last week.